diff --git a/lexer.js b/lexer.js
index 1614fd9..664b729 100755
--- a/lexer.js
+++ b/lexer.js
@@ -1,4 +1,5 @@
 let source, pos, end;
+const STACK_DEPTH = 2048;
 let openTokenDepth,
   templateDepth,
   lastTokenPos,
@@ -37,6 +38,20 @@ const Import = 0;
 const ExportAssign = 1;
 const ExportStar = 2;
 
+/** @param {number} tokenPos */
+function pushOpenToken (tokenPos) {
+  if (openTokenDepth === STACK_DEPTH)
+    throw new Error('Maximum nesting depth exceeded.');
+  openTokenPosStack[openTokenDepth++] = tokenPos;
+}
+
+function pushTemplate () {
+  if (templateStackDepth === STACK_DEPTH || openTokenDepth === STACK_DEPTH)
+    throw new Error('Maximum nesting depth exceeded.');
+  templateStack[templateStackDepth++] = templateDepth;
+  templateDepth = ++openTokenDepth;
+}
+
 function parseCJS (source, name = '@') {
   resetState();
   try {
@@ -125,7 +140,7 @@ function parseSource (cjsSource) {
             pos += 23;
             if (source.charCodeAt(pos) === 40/*(*/) {
               pos++;
-              openTokenPosStack[openTokenDepth++] = lastTokenPos;
+              pushOpenToken(lastTokenPos);
               if (tryParseRequire(Import) && keywordStart(startPos)) {
                 tryBacktrackAddStarExportBinding(startPos - 1);
               }
@@ -136,7 +151,7 @@ function parseSource (cjsSource) {
             if (source.startsWith('Star', pos))
               pos += 4;
             if (source.charCodeAt(pos) === 40/*(*/) {
-              openTokenPosStack[openTokenDepth++] = lastTokenPos;
+              pushOpenToken(lastTokenPos);
               if (source.charCodeAt(pos + 1) === 114/*r*/) {
                 pos++;
                 tryParseRequire(ExportStar);
@@ -170,7 +185,7 @@ function parseSource (cjsSource) {
           tryParseObjectDefineOrKeys(openTokenDepth === 0);
         break;
       case 40/*(*/:
-        openTokenPosStack[openTokenDepth++] = lastTokenPos;
+        pushOpenToken(lastTokenPos);
         break;
       case 41/*)*/:
         if (openTokenDepth === 0)
@@ -178,9 +193,9 @@ function parseSource (cjsSource) {
         openTokenDepth--;
         break;
       case 123/*{*/:
-        openClassPosStack[openTokenDepth] = nextBraceIsClass;
+        pushOpenToken(lastTokenPos);
+        openClassPosStack[openTokenDepth - 1] = nextBraceIsClass;
         nextBraceIsClass = false;
-        openTokenPosStack[openTokenDepth++] = lastTokenPos;
         break;
       case 125/*}*/:
         if (openTokenDepth === 0)
@@ -1324,7 +1339,7 @@ function throwIfImportStatement () {
   switch (ch) {
     // dynamic import
     case 40/*(*/:
-      openTokenPosStack[openTokenDepth++] = startPos;
+      pushOpenToken(startPos);
       return;
     // import.meta
     case 46/*.*/:
@@ -1382,8 +1397,7 @@ function templateString () {
     const ch = source.charCodeAt(pos);
     if (ch === 36/*$*/ && source.charCodeAt(pos + 1) === 123/*{*/) {
       pos++;
-      templateStack[templateStackDepth++] = templateDepth;
-      templateDepth = ++openTokenDepth;
+      pushTemplate();
       return;
     }
     if (ch === 96/*`*/)
diff --git a/lib/lexer.wasm b/lib/lexer.wasm
index 3ff889c..577fbed 100755
Binary files a/lib/lexer.wasm and b/lib/lexer.wasm differ
diff --git a/lib/lexer.wat b/lib/lexer.wat
index 7f1fad4..85155c9 100644
--- a/lib/lexer.wat
+++ b/lib/lexer.wat
@@ -439,53 +439,250 @@
                                       block  ;; label = @18
                                         block  ;; label = @19
                                           block  ;; label = @20
-                                            i32.const 0
-                                            i32.load16_u offset=8198
-                                            local.tee 3
-                                            br_if 0 (;@20;)
                                             block  ;; label = @21
                                               block  ;; label = @22
+                                                i32.const 0
+                                                i32.load16_u offset=8198
+                                                local.tee 3
+                                                br_if 0 (;@22;)
                                                 block  ;; label = @23
-                                                  local.get 1
-                                                  i32.const -95
-                                                  i32.add
-                                                  br_table 2 (;@21;) 16 (;@7;) 19 (;@4;) 19 (;@4;) 6 (;@17;) 19 (;@4;) 5 (;@18;) 19 (;@4;) 19 (;@4;) 19 (;@4;) 1 (;@22;) 19 (;@4;) 19 (;@4;) 19 (;@4;) 4 (;@19;) 0 (;@23;)
-                                                end
-                                                block  ;; label = @23
-                                                  local.get 1
-                                                  i32.const -39
-                                                  i32.add
-                                                  br_table 14 (;@9;) 8 (;@15;) 9 (;@14;) 19 (;@4;) 19 (;@4;) 19 (;@4;) 19 (;@4;) 19 (;@4;) 15 (;@8;) 0 (;@23;)
-                                                end
-                                                block  ;; label = @23
-                                                  local.get 1
-                                                  i32.const -123
-                                                  i32.add
-                                                  br_table 11 (;@12;) 19 (;@4;) 12 (;@11;) 0 (;@23;)
+                                                  block  ;; label = @24
+                                                    block  ;; label = @25
+                                                      local.get 1
+                                                      i32.const -95
+                                                      i32.add
+                                                      br_table 2 (;@23;) 18 (;@7;) 21 (;@4;) 21 (;@4;) 6 (;@19;) 21 (;@4;) 5 (;@20;) 21 (;@4;) 21 (;@4;) 21 (;@4;) 1 (;@24;) 21 (;@4;) 21 (;@4;) 21 (;@4;) 4 (;@21;) 0 (;@25;)
+                                                    end
+                                                    block  ;; label = @25
+                                                      local.get 1
+                                                      i32.const -39
+                                                      i32.add
+                                                      br_table 16 (;@9;) 9 (;@16;) 10 (;@15;) 21 (;@4;) 21 (;@4;) 21 (;@4;) 21 (;@4;) 21 (;@4;) 17 (;@8;) 0 (;@25;)
+                                                    end
+                                                    block  ;; label = @25
+                                                      local.get 1
+                                                      i32.const -123
+                                                      i32.add
+                                                      br_table 13 (;@12;) 21 (;@4;) 14 (;@11;) 0 (;@25;)
+                                                    end
+                                                    local.get 1
+                                                    i32.const 34
+                                                    i32.eq
+                                                    br_if 15 (;@9;)
+                                                    local.get 1
+                                                    i32.const 79
+                                                    i32.eq
+                                                    br_if 6 (;@18;)
+                                                    local.get 1
+                                                    i32.const 114
+                                                    i32.ne
+                                                    br_if 20 (;@4;)
+                                                    block  ;; label = @25
+                                                      i32.const 0
+                                                      call 16
+                                                      i32.eqz
+                                                      br_if 0 (;@25;)
+                                                      local.get 0
+                                                      call 17
+                                                      i32.eqz
+                                                      br_if 0 (;@25;)
+                                                      local.get 4
+                                                      call 18
+                                                    end
+                                                    i32.const 0
+                                                    i32.const 0
+                                                    i32.load offset=20540
+                                                    i32.store offset=8204
+                                                    br 21 (;@3;)
+                                                  end
+                                                  block  ;; label = @24
+                                                    local.get 4
+                                                    i32.const 4
+                                                    i32.add
+                                                    i32.const 109
+                                                    i32.const 112
+                                                    i32.const 111
+                                                    i32.const 114
+                                                    i32.const 116
+                                                    call 19
+                                                    i32.eqz
+                                                    br_if 0 (;@24;)
+                                                    local.get 0
+                                                    call 17
+                                                    i32.eqz
+                                                    br_if 0 (;@24;)
+                                                    call 20
+                                                    i32.const 0
+                                                    i32.load offset=20540
+                                                    local.set 0
+                                                  end
+                                                  i32.const 0
+                                                  local.get 0
+                                                  i32.store offset=8204
+                                                  br 20 (;@3;)
                                                 end
-                                                local.get 1
-                                                i32.const 34
-                                                i32.eq
-                                                br_if 13 (;@9;)
-                                                local.get 1
-                                                i32.const 79
-                                                i32.eq
-                                                br_if 6 (;@16;)
-                                                local.get 1
-                                                i32.const 114
-                                                i32.ne
-                                                br_if 18 (;@4;)
                                                 block  ;; label = @23
-                                                  i32.const 0
-                                                  call 16
+                                                  block  ;; label = @24
+                                                    local.get 4
+                                                    i32.const 4
+                                                    i32.add
+                                                    local.tee 3
+                                                    i32.const 105
+                                                    i32.const 110
+                                                    i32.const 116
+                                                    i32.const 101
+                                                    i32.const 114
+                                                    i32.const 111
+                                                    i32.const 112
+                                                    i32.const 82
+                                                    i32.const 101
+                                                    i32.const 113
+                                                    i32.const 117
+                                                    i32.const 105
+                                                    i32.const 114
+                                                    i32.const 101
+                                                    i32.const 87
+                                                    i32.const 105
+                                                    i32.const 108
+                                                    i32.const 100
+                                                    i32.const 99
+                                                    i32.const 97
+                                                    i32.const 114
+                                                    i32.const 100
+                                                    call 21
+                                                    i32.eqz
+                                                    br_if 0 (;@24;)
+                                                    block  ;; label = @25
+                                                      local.get 0
+                                                      call 17
+                                                      br_if 0 (;@25;)
+                                                      local.get 4
+                                                      i32.load16_u
+                                                      i32.const 46
+                                                      i32.ne
+                                                      br_if 1 (;@24;)
+                                                    end
+                                                    i32.const 0
+                                                    local.get 4
+                                                    i32.const 48
+                                                    i32.add
+                                                    i32.store offset=20540
+                                                    local.get 4
+                                                    i32.load16_u offset=48
+                                                    i32.const 40
+                                                    i32.ne
+                                                    br_if 1 (;@23;)
+                                                    i32.const 0
+                                                    local.get 4
+                                                    i32.const 50
+                                                    i32.add
+                                                    i32.store offset=20540
+                                                    i32.const 0
+                                                    i32.const 1
+                                                    i32.store16 offset=8198
+                                                    i32.const 0
+                                                    i32.load offset=20528
+                                                    i32.const 0
+                                                    i32.load offset=8204
+                                                    i32.store
+                                                    i32.const 0
+                                                    call 16
+                                                    i32.eqz
+                                                    br_if 1 (;@23;)
+                                                    local.get 0
+                                                    call 17
+                                                    i32.eqz
+                                                    br_if 1 (;@23;)
+                                                    local.get 4
+                                                    call 18
+                                                    br 1 (;@23;)
+                                                  end
+                                                  local.get 3
+                                                  i32.const 95
+                                                  i32.const 101
+                                                  i32.const 120
+                                                  i32.const 112
+                                                  i32.const 111
+                                                  i32.const 114
+                                                  i32.const 116
+                                                  call 22
                                                   i32.eqz
                                                   br_if 0 (;@23;)
-                                                  local.get 0
-                                                  call 17
-                                                  i32.eqz
+                                                  block  ;; label = @24
+                                                    local.get 0
+                                                    call 17
+                                                    br_if 0 (;@24;)
+                                                    local.get 4
+                                                    i32.load16_u
+                                                    i32.const 46
+                                                    i32.ne
+                                                    br_if 1 (;@23;)
+                                                  end
+                                                  i32.const 0
+                                                  local.get 4
+                                                  i32.const 18
+                                                  i32.add
+                                                  i32.store offset=20540
+                                                  block  ;; label = @24
+                                                    local.get 4
+                                                    i32.load16_u offset=18
+                                                    local.tee 3
+                                                    i32.const 83
+                                                    i32.ne
+                                                    br_if 0 (;@24;)
+                                                    local.get 4
+                                                    i32.load16_u offset=20
+                                                    i32.const 116
+                                                    i32.ne
+                                                    br_if 1 (;@23;)
+                                                    local.get 4
+                                                    i32.load16_u offset=22
+                                                    i32.const 97
+                                                    i32.ne
+                                                    br_if 1 (;@23;)
+                                                    local.get 4
+                                                    i32.load16_u offset=24
+                                                    i32.const 114
+                                                    i32.ne
+                                                    br_if 1 (;@23;)
+                                                    i32.const 0
+                                                    local.get 4
+                                                    i32.const 26
+                                                    i32.add
+                                                    i32.store offset=20540
+                                                    local.get 4
+                                                    i32.load16_u offset=26
+                                                    local.set 3
+                                                  end
+                                                  local.get 3
+                                                  i32.const 65535
+                                                  i32.and
+                                                  i32.const 40
+                                                  i32.ne
                                                   br_if 0 (;@23;)
+                                                  i32.const 0
+                                                  i32.load offset=20528
+                                                  i32.const 0
+                                                  i32.load offset=8204
+                                                  i32.store
+                                                  i32.const 0
+                                                  i32.const 1
+                                                  i32.store16 offset=8198
+                                                  i32.const 0
+                                                  i32.load offset=20540
+                                                  local.tee 4
+                                                  i32.load16_u offset=2
+                                                  i32.const 114
+                                                  i32.ne
+                                                  br_if 0 (;@23;)
+                                                  i32.const 0
                                                   local.get 4
-                                                  call 18
+                                                  i32.const 2
+                                                  i32.add
+                                                  i32.store offset=20540
+                                                  i32.const 2
+                                                  call 16
+                                                  drop
                                                 end
                                                 i32.const 0
                                                 i32.const 0
@@ -494,256 +691,125 @@
                                                 br 19 (;@3;)
                                               end
                                               block  ;; label = @22
-                                                local.get 4
-                                                i32.const 4
+                                                local.get 1
+                                                i32.const -39
                                                 i32.add
-                                                i32.const 109
-                                                i32.const 112
-                                                i32.const 111
-                                                i32.const 114
-                                                i32.const 116
-                                                call 19
-                                                i32.eqz
-                                                br_if 0 (;@22;)
-                                                local.get 0
-                                                call 17
-                                                i32.eqz
-                                                br_if 0 (;@22;)
-                                                call 20
-                                                i32.const 0
-                                                i32.load offset=20540
-                                                local.set 0
+                                                br_table 13 (;@9;) 5 (;@17;) 8 (;@14;) 18 (;@4;) 18 (;@4;) 18 (;@4;) 18 (;@4;) 18 (;@4;) 14 (;@8;) 0 (;@22;)
                                               end
-                                              i32.const 0
-                                              local.get 0
-                                              i32.store offset=8204
-                                              br 18 (;@3;)
-                                            end
-                                            block  ;; label = @21
                                               block  ;; label = @22
-                                                local.get 4
-                                                i32.const 4
-                                                i32.add
-                                                local.tee 3
-                                                i32.const 105
-                                                i32.const 110
-                                                i32.const 116
-                                                i32.const 101
-                                                i32.const 114
-                                                i32.const 111
-                                                i32.const 112
-                                                i32.const 82
-                                                i32.const 101
-                                                i32.const 113
-                                                i32.const 117
-                                                i32.const 105
-                                                i32.const 114
-                                                i32.const 101
-                                                i32.const 87
-                                                i32.const 105
-                                                i32.const 108
-                                                i32.const 100
-                                                i32.const 99
-                                                i32.const 97
-                                                i32.const 114
-                                                i32.const 100
-                                                call 21
-                                                i32.eqz
-                                                br_if 0 (;@22;)
-                                                block  ;; label = @23
-                                                  local.get 0
-                                                  call 17
-                                                  br_if 0 (;@23;)
-                                                  local.get 4
-                                                  i32.load16_u
-                                                  i32.const 46
-                                                  i32.ne
-                                                  br_if 1 (;@22;)
-                                                end
-                                                i32.const 0
-                                                local.get 4
-                                                i32.const 48
-                                                i32.add
-                                                i32.store offset=20540
-                                                local.get 4
-                                                i32.load16_u offset=48
-                                                i32.const 40
-                                                i32.ne
-                                                br_if 1 (;@21;)
-                                                i32.const 0
-                                                local.get 4
-                                                i32.const 50
+                                                local.get 1
+                                                i32.const -96
                                                 i32.add
-                                                i32.store offset=20540
-                                                i32.const 0
-                                                i32.const 1
-                                                i32.store16 offset=8198
-                                                i32.const 0
-                                                i32.load offset=20528
-                                                i32.const 0
-                                                i32.load offset=8204
-                                                i32.store
-                                                i32.const 0
-                                                call 16
-                                                i32.eqz
-                                                br_if 1 (;@21;)
-                                                local.get 0
-                                                call 17
-                                                i32.eqz
-                                                br_if 1 (;@21;)
-                                                local.get 4
-                                                call 18
-                                                br 1 (;@21;)
+                                                br_table 15 (;@7;) 18 (;@4;) 18 (;@4;) 3 (;@19;) 18 (;@4;) 2 (;@20;) 0 (;@22;)
                                               end
-                                              local.get 3
-                                              i32.const 95
-                                              i32.const 101
-                                              i32.const 120
-                                              i32.const 112
-                                              i32.const 111
-                                              i32.const 114
-                                              i32.const 116
-                                              call 22
-                                              i32.eqz
-                                              br_if 0 (;@21;)
                                               block  ;; label = @22
-                                                local.get 0
-                                                call 17
-                                                br_if 0 (;@22;)
-                                                local.get 4
-                                                i32.load16_u
-                                                i32.const 46
-                                                i32.ne
-                                                br_if 1 (;@21;)
-                                              end
-                                              i32.const 0
-                                              local.get 4
-                                              i32.const 18
-                                              i32.add
-                                              i32.store offset=20540
-                                              block  ;; label = @22
-                                                local.get 4
-                                                i32.load16_u offset=18
-                                                local.tee 3
-                                                i32.const 83
-                                                i32.ne
-                                                br_if 0 (;@22;)
-                                                local.get 4
-                                                i32.load16_u offset=20
-                                                i32.const 116
-                                                i32.ne
-                                                br_if 1 (;@21;)
-                                                local.get 4
-                                                i32.load16_u offset=22
-                                                i32.const 97
-                                                i32.ne
-                                                br_if 1 (;@21;)
-                                                local.get 4
-                                                i32.load16_u offset=24
-                                                i32.const 114
-                                                i32.ne
-                                                br_if 1 (;@21;)
-                                                i32.const 0
-                                                local.get 4
-                                                i32.const 26
+                                                local.get 1
+                                                i32.const -123
                                                 i32.add
-                                                i32.store offset=20540
-                                                local.get 4
-                                                i32.load16_u offset=26
-                                                local.set 3
+                                                br_table 9 (;@13;) 18 (;@4;) 12 (;@10;) 0 (;@22;)
                                               end
-                                              local.get 3
-                                              i32.const 65535
-                                              i32.and
-                                              i32.const 40
+                                              local.get 1
+                                              i32.const 34
+                                              i32.eq
+                                              br_if 12 (;@9;)
+                                              local.get 1
+                                              i32.const 79
+                                              i32.eq
+                                              br_if 3 (;@18;)
+                                              local.get 1
+                                              i32.const 109
                                               i32.ne
-                                              br_if 0 (;@21;)
-                                              i32.const 0
-                                              i32.load offset=20528
-                                              i32.const 0
-                                              i32.load offset=8204
-                                              i32.store
-                                              i32.const 0
-                                              i32.const 1
-                                              i32.store16 offset=8198
-                                              i32.const 0
-                                              i32.load offset=20540
-                                              local.tee 4
-                                              i32.load16_u offset=2
-                                              i32.const 114
-                                              i32.ne
-                                              br_if 0 (;@21;)
-                                              i32.const 0
-                                              local.get 4
-                                              i32.const 2
-                                              i32.add
-                                              i32.store offset=20540
-                                              i32.const 2
-                                              call 16
-                                              drop
+                                              br_if 17 (;@4;)
                                             end
-                                            i32.const 0
-                                            i32.const 0
-                                            i32.load offset=20540
-                                            i32.store offset=8204
-                                            br 17 (;@3;)
-                                          end
-                                          block  ;; label = @20
-                                            local.get 1
-                                            i32.const -39
+                                            local.get 4
+                                            i32.const 4
                                             i32.add
-                                            br_table 11 (;@9;) 5 (;@15;) 7 (;@13;) 16 (;@4;) 16 (;@4;) 16 (;@4;) 16 (;@4;) 16 (;@4;) 12 (;@8;) 0 (;@20;)
-                                          end
-                                          block  ;; label = @20
-                                            local.get 1
-                                            i32.const -96
-                                            i32.add
-                                            br_table 13 (;@7;) 16 (;@4;) 16 (;@4;) 3 (;@17;) 16 (;@4;) 2 (;@18;) 0 (;@20;)
+                                            i32.const 111
+                                            i32.const 100
+                                            i32.const 117
+                                            i32.const 108
+                                            i32.const 101
+                                            call 19
+                                            i32.eqz
+                                            br_if 16 (;@4;)
+                                            local.get 0
+                                            call 17
+                                            i32.eqz
+                                            br_if 16 (;@4;)
+                                            call 23
+                                            br 16 (;@4;)
                                           end
+                                          local.get 4
+                                          i32.const 4
+                                          i32.add
+                                          i32.const 120
+                                          i32.const 112
+                                          i32.const 111
+                                          i32.const 114
+                                          i32.const 116
+                                          call 19
+                                          i32.eqz
+                                          br_if 15 (;@4;)
+                                          local.get 0
+                                          call 17
+                                          i32.eqz
+                                          br_if 15 (;@4;)
                                           block  ;; label = @20
-                                            local.get 1
-                                            i32.const -123
-                                            i32.add
-                                            br_table 8 (;@12;) 16 (;@4;) 10 (;@10;) 0 (;@20;)
+                                            local.get 4
+                                            i32.load16_u offset=14
+                                            i32.const 115
+                                            i32.ne
+                                            br_if 0 (;@20;)
+                                            i32.const 0
+                                            call 24
+                                            br 16 (;@4;)
                                           end
-                                          local.get 1
-                                          i32.const 34
-                                          i32.eq
-                                          br_if 10 (;@9;)
-                                          local.get 1
-                                          i32.const 79
-                                          i32.eq
-                                          br_if 3 (;@16;)
-                                          local.get 1
-                                          i32.const 109
-                                          i32.ne
+                                          local.get 3
                                           br_if 15 (;@4;)
+                                          call 25
+                                          br 15 (;@4;)
                                         end
+                                        local.get 0
+                                        call 17
+                                        i32.eqz
+                                        br_if 14 (;@4;)
                                         local.get 4
-                                        i32.const 4
-                                        i32.add
-                                        i32.const 111
-                                        i32.const 100
-                                        i32.const 117
+                                        i32.load16_u offset=4
                                         i32.const 108
-                                        i32.const 101
-                                        call 19
-                                        i32.eqz
+                                        i32.ne
                                         br_if 14 (;@4;)
-                                        local.get 0
-                                        call 17
+                                        local.get 4
+                                        i32.load16_u offset=6
+                                        i32.const 97
+                                        i32.ne
+                                        br_if 14 (;@4;)
+                                        local.get 4
+                                        i32.load16_u offset=8
+                                        i32.const 115
+                                        i32.ne
+                                        br_if 14 (;@4;)
+                                        local.get 4
+                                        i32.load16_u offset=10
+                                        i32.const 115
+                                        i32.ne
+                                        br_if 14 (;@4;)
+                                        local.get 4
+                                        i32.load16_u offset=12
+                                        call 26
                                         i32.eqz
                                         br_if 14 (;@4;)
-                                        call 23
+                                        i32.const 0
+                                        i32.const 1
+                                        i32.store8 offset=20536
                                         br 14 (;@4;)
                                       end
                                       local.get 4
                                       i32.const 4
                                       i32.add
-                                      i32.const 120
-                                      i32.const 112
-                                      i32.const 111
-                                      i32.const 114
+                                      i32.const 98
+                                      i32.const 106
+                                      i32.const 101
+                                      i32.const 99
                                       i32.const 116
                                       call 19
                                       i32.eqz
@@ -752,114 +818,65 @@
                                       call 17
                                       i32.eqz
                                       br_if 13 (;@4;)
-                                      block  ;; label = @18
-                                        local.get 4
-                                        i32.load16_u offset=14
-                                        i32.const 115
-                                        i32.ne
-                                        br_if 0 (;@18;)
-                                        i32.const 0
-                                        call 24
-                                        br 14 (;@4;)
-                                      end
                                       local.get 3
-                                      br_if 13 (;@4;)
-                                      call 25
+                                      i32.eqz
+                                      call 27
                                       br 13 (;@4;)
                                     end
-                                    local.get 0
-                                    call 17
-                                    i32.eqz
-                                    br_if 12 (;@4;)
-                                    local.get 4
-                                    i32.load16_u offset=4
-                                    i32.const 108
+                                    local.get 3
+                                    i32.const 2048
                                     i32.ne
-                                    br_if 12 (;@4;)
-                                    local.get 4
-                                    i32.load16_u offset=6
-                                    i32.const 97
-                                    i32.ne
-                                    br_if 12 (;@4;)
-                                    local.get 4
-                                    i32.load16_u offset=8
-                                    i32.const 115
-                                    i32.ne
-                                    br_if 12 (;@4;)
-                                    local.get 4
-                                    i32.load16_u offset=10
-                                    i32.const 115
-                                    i32.ne
-                                    br_if 12 (;@4;)
-                                    local.get 4
-                                    i32.load16_u offset=12
-                                    call 26
-                                    i32.eqz
-                                    br_if 12 (;@4;)
+                                    br_if 0 (;@16;)
+                                    i32.const 12
+                                    call 28
                                     i32.const 0
-                                    i32.const 1
-                                    i32.store8 offset=20536
-                                    br 12 (;@4;)
+                                    i32.load offset=4080
+                                    return
                                   end
-                                  local.get 4
-                                  i32.const 4
+                                  i32.const 0
+                                  local.get 3
+                                  i32.const 1
                                   i32.add
-                                  i32.const 98
-                                  i32.const 106
-                                  i32.const 101
-                                  i32.const 99
-                                  i32.const 116
-                                  call 19
-                                  i32.eqz
-                                  br_if 11 (;@4;)
-                                  local.get 0
-                                  call 17
-                                  i32.eqz
-                                  br_if 11 (;@4;)
+                                  i32.store16 offset=8198
+                                  i32.const 0
+                                  i32.load offset=20528
                                   local.get 3
-                                  i32.eqz
-                                  call 27
+                                  i32.const 2
+                                  i32.shl
+                                  i32.add
+                                  i32.const 0
+                                  i32.load offset=8204
+                                  i32.store
                                   br 11 (;@4;)
                                 end
+                                i32.const 8
+                                call 28
                                 i32.const 0
-                                local.get 3
-                                i32.const 1
-                                i32.add
-                                i32.store16 offset=8198
-                                i32.const 0
-                                i32.load offset=20528
-                                local.get 3
-                                i32.const 2
-                                i32.shl
-                                i32.add
-                                i32.const 0
-                                i32.load offset=8204
-                                i32.store
-                                br 10 (;@4;)
+                                i32.load offset=4080
+                                return
                               end
-                              i32.const 8
-                              call 28
                               i32.const 0
-                              i32.load offset=4080
-                              return
+                              local.get 3
+                              i32.const -1
+                              i32.add
+                              i32.store16 offset=8198
+                              br 9 (;@4;)
                             end
-                            i32.const 0
                             local.get 3
-                            i32.const -1
-                            i32.add
-                            i32.store16 offset=8198
-                            br 8 (;@4;)
+                            i32.const 2048
+                            i32.ne
+                            br_if 0 (;@12;)
+                            i32.const 12
+                            call 28
+                            i32.const 0
+                            i32.load offset=4080
+                            return
                           end
-                          local.get 3
-                          i32.const 20560
-                          i32.add
-                          i32.const 0
-                          i32.load8_u offset=20536
-                          i32.store8
                           i32.const 0
                           local.get 3
                           i32.const 1
                           i32.add
+                          local.tee 4
                           i32.store16 offset=8198
                           i32.const 0
                           i32.load offset=20528
@@ -870,6 +887,14 @@
                           i32.const 0
                           i32.load offset=8204
                           i32.store
+                          local.get 4
+                          i32.const 65535
+                          i32.and
+                          i32.const 20559
+                          i32.add
+                          i32.const 0
+                          i32.load8_u offset=20536
+                          i32.store8
                           i32.const 0
                           i32.const 0
                           i32.store8 offset=20536
@@ -1498,10 +1523,19 @@
             i32.store offset=20540
             return
           end
+          block  ;; label = @4
+            i32.const 0
+            i32.load16_u offset=8198
+            local.tee 2
+            i32.const 2048
+            i32.ne
+            br_if 0 (;@4;)
+            i32.const 12
+            call 28
+            return
+          end
           i32.const 0
-          i32.const 0
-          i32.load16_u offset=8198
-          local.tee 2
+          local.get 2
           i32.const 1
           i32.add
           i32.store16 offset=8198
@@ -4713,9 +4747,32 @@
             i32.ne
             br_if 1 (;@3;)
             i32.const 0
+            local.get 2
+            i32.const 4
+            i32.add
+            i32.store offset=20540
+            block  ;; label = @5
+              block  ;; label = @6
+                i32.const 0
+                i32.load16_u offset=8196
+                local.tee 0
+                i32.const 2048
+                i32.eq
+                br_if 0 (;@6;)
+                i32.const 0
+                i32.load16_u offset=8198
+                i32.const 65535
+                i32.and
+                i32.const 2048
+                i32.ne
+                br_if 1 (;@5;)
+              end
+              i32.const 12
+              call 28
+              return
+            end
             i32.const 0
-            i32.load16_u offset=8196
-            local.tee 0
+            local.get 0
             i32.const 1
             i32.add
             i32.store16 offset=8196
@@ -4729,11 +4786,6 @@
             i32.load16_u offset=8200
             i32.store16
             i32.const 0
-            local.get 2
-            i32.const 4
-            i32.add
-            i32.store offset=20540
-            i32.const 0
             i32.const 0
             i32.load16_u offset=8198
             i32.const 1
diff --git a/src/lexer.c b/src/lexer.c
index fd7ba8b..e688f21 100755
--- a/src/lexer.c
+++ b/src/lexer.c
@@ -44,6 +44,25 @@ void (*addReexport)(const uint16_t*, const uint16_t*);
 void (*addUnsafeGetter)(const uint16_t*, const uint16_t*);
 void (*clearReexports)();
 
+static inline __attribute__((always_inline)) bool pushOpenToken (uint16_t* tokenPos) {
+  if (openTokenDepth == STACK_DEPTH) {
+    syntaxError(12);
+    return false;
+  }
+  openTokenPosStack[openTokenDepth++] = tokenPos;
+  return true;
+}
+
+static inline __attribute__((always_inline)) bool pushTemplate () {
+  if (templateStackDepth == STACK_DEPTH || openTokenDepth == STACK_DEPTH) {
+    syntaxError(12);
+    return false;
+  }
+  templateStack[templateStackDepth++] = templateDepth;
+  templateDepth = ++openTokenDepth;
+  return true;
+}
+
 // Note: parsing is based on the _assumption_ that the source is already valid
 uint32_t parseCJS (uint16_t* _source, uint32_t _sourceLen, void (*_addExport)(const uint16_t*, const uint16_t*), void (*_addReexport)(const uint16_t*, const uint16_t*), void (*_addUnsafeGetter)(const uint16_t*, const uint16_t*), void (*_clearReexports)()) {
   source = _source;
@@ -109,7 +128,8 @@ uint32_t parseCJS (uint16_t* _source, uint32_t _sourceLen, void (*_addExport)(co
             pos += 23;
             if (*pos == '(') {
               pos++;
-              openTokenPosStack[openTokenDepth++] = lastTokenPos;
+              if (!pushOpenToken(lastTokenPos))
+                return error;
               if (tryParseRequire(Import) && keywordStart(startPos))
                 tryBacktrackAddStarExportBinding(startPos - 1);
             }
@@ -119,7 +139,8 @@ uint32_t parseCJS (uint16_t* _source, uint32_t _sourceLen, void (*_addExport)(co
             if (str_eq4(pos, 'S', 't', 'a', 'r'))
               pos += 4;
             if (*pos == '(') {
-              openTokenPosStack[openTokenDepth++] = lastTokenPos;
+              if (!pushOpenToken(lastTokenPos))
+                return error;
               if (*(pos + 1) == 'r') {
                 pos++;
                 tryParseRequire(ExportStar);
@@ -153,7 +174,8 @@ uint32_t parseCJS (uint16_t* _source, uint32_t _sourceLen, void (*_addExport)(co
           tryParseObjectDefineOrKeys(openTokenDepth == 0);
         break;
       case '(':
-        openTokenPosStack[openTokenDepth++] = lastTokenPos;
+        if (!pushOpenToken(lastTokenPos))
+          return error;
         break;
       case ')':
         if (openTokenDepth == 0)
@@ -161,9 +183,10 @@ uint32_t parseCJS (uint16_t* _source, uint32_t _sourceLen, void (*_addExport)(co
         openTokenDepth--;
         break;
       case '{':
-        openClassPosStack[openTokenDepth] = nextBraceIsClass;
+        if (!pushOpenToken(lastTokenPos))
+          return error;
+        openClassPosStack[openTokenDepth - 1] = nextBraceIsClass;
         nextBraceIsClass = false;
-        openTokenPosStack[openTokenDepth++] = lastTokenPos;
         break;
       case '}':
         if (openTokenDepth == 0)
@@ -1152,7 +1175,8 @@ void throwIfImportStatement () {
   switch (ch) {
     // dynamic import
     case '(':
-      openTokenPosStack[openTokenDepth++] = startPos;
+      if (!pushOpenToken(startPos))
+        return;
       return;
     // import.meta
     case '.':
@@ -1211,8 +1235,8 @@ void templateString () {
     uint16_t ch = *pos;
     if (ch == '$' && *(pos + 1) == '{') {
       pos++;
-      templateStack[templateStackDepth++] = templateDepth;
-      templateDepth = ++openTokenDepth;
+      if (!pushTemplate())
+        return;
       return;
     }
     if (ch == '`')
diff --git a/test/_unit.js b/test/_unit.js
index 0458f17..4a3e94c 100755
--- a/test/_unit.js
+++ b/test/_unit.js
@@ -887,6 +887,69 @@ function x() {
     `));
   });
 
+  test('Nesting depth boundaries', () => {
+    const stackDepth = 2048;
+    const expressionNesting = [
+      ['(', ')'],
+      ['import(', ')'],
+      ['class A{a=', '}'],
+      ['`${', '}`']
+    ];
+
+    /**
+     * @param {number} depth
+     */
+    function mixedSource (depth) {
+      const braceDepth = Math.floor(depth / 5);
+      const expressionDepth = depth - braceDepth;
+      const openings = new Array(expressionDepth);
+      const closings = new Array(expressionDepth);
+      for (let index = 0; index < expressionDepth; index++) {
+        const [opening, closing] = expressionNesting[index % expressionNesting.length];
+        openings[index] = opening;
+        closings[expressionDepth - index - 1] = closing;
+      }
+      return '{'.repeat(braceDepth) + openings.join('') + '0' + closings.join('') +
+        ';' + '}'.repeat(braceDepth);
+    }
+
+    const sources = [
+      [
+        '('.repeat(stackDepth) + '0' + ')'.repeat(stackDepth),
+        '('.repeat(stackDepth + 1) + '0' + ')'.repeat(stackDepth + 1)
+      ],
+      [
+        '{'.repeat(stackDepth) + '0;' + '}'.repeat(stackDepth),
+        '{'.repeat(stackDepth + 1) + '0;' + '}'.repeat(stackDepth + 1)
+      ],
+      [
+        '`${'.repeat(stackDepth) + '0' + '}`'.repeat(stackDepth),
+        '`${'.repeat(stackDepth + 1) + '0' + '}`'.repeat(stackDepth + 1)
+      ],
+      [
+        'class A{a='.repeat(stackDepth) + '0' + '}'.repeat(stackDepth),
+        'class A{a='.repeat(stackDepth + 1) + '0' + '}'.repeat(stackDepth + 1)
+      ],
+      [
+        'import('.repeat(stackDepth) + '"x"' + ')'.repeat(stackDepth),
+        'import('.repeat(stackDepth + 1) + '"x"' + ')'.repeat(stackDepth + 1)
+      ],
+      [
+        mixedSource(stackDepth),
+        mixedSource(stackDepth + 1)
+      ]
+    ];
+    const expectedError = process.env.WASM || process.env.WASM_SYNC
+      ? /^Error: Parse error @/
+      : /^Error: Maximum nesting depth exceeded\./;
+
+    for (const [accepted, rejected] of sources) {
+      assert.deepStrictEqual(parse(accepted), { exports: [], reexports: [] });
+      assert.throws(() => parse(rejected), expectedError);
+      assert.deepStrictEqual(parse('exports.after = 1'), { exports: ['after'], reexports: [] });
+    }
+  });
+
   test('Division / Regex ambiguity', () => {
     const source = `
       /as)df/; x();