diff --git a/internal/cbm/vendored/grammars/swift/scanner.c b/internal/cbm/vendored/grammars/swift/scanner.c
index 2615afe43..bb2dcac58 100644
--- a/internal/cbm/vendored/grammars/swift/scanner.c
+++ b/internal/cbm/vendored/grammars/swift/scanner.c
@@ -511,7 +511,7 @@ static bool eat_operators(
         uint64_t suppressing_symbols = OP_SYMBOL_SUPPRESSOR[full_match];
         if (suppressing_symbols) {
             for (uint64_t suppressor = 0; suppressor < TOKEN_COUNT; suppressor++) {
-                if (!(suppressing_symbols & 1 << suppressor)) {
+                if (!(suppressing_symbols & 1ULL << suppressor)) {
                     continue;
                 }
 
diff --git a/scripts/vendored-checksums.txt b/scripts/vendored-checksums.txt
index 991a684aa..9531f343d 100644
--- a/scripts/vendored-checksums.txt
+++ b/scripts/vendored-checksums.txt
@@ -787,7 +787,7 @@ c71d239df91726fc519c6eb72d318ec65820627232b2f796219e87dcf35d0ab4  internal/cbm/v
 2db740ea1be6b71014d2be1385491f01bf2d15b607e61c5b30b4128535efe68a  internal/cbm/vendored/grammars/sway/tree_sitter/parser.h
 3533cec129bb4bba015c0d61d86dd7c3b7e82110e4d2ff7837a01eff5bad5ccc  internal/cbm/vendored/grammars/swift/LICENSE
 93e6b39fc5b16ef9d5869862ec8d56380a838355c362481942942d59ca666de2  internal/cbm/vendored/grammars/swift/parser.c
-b835c1ded068e902944fe82c3770b9dcf85f67dcaab8fbf772f1606007da7373  internal/cbm/vendored/grammars/swift/scanner.c
+f3d6271d64f58c39eed544104a70ca2cf9ecbf80c5d900620f1afd38836542cb  internal/cbm/vendored/grammars/swift/scanner.c
 b29c1c9fb7cc82f58c84b376df1297d6e2737a1d655fd356db0859e3c29c2fea  internal/cbm/vendored/grammars/swift/tree_sitter/alloc.h
 5bdf6ed1a78e3409fd443e085ca967a64c188a5d082aaf7f819bccd53a471c94  internal/cbm/vendored/grammars/swift/tree_sitter/array.h
 a1f6ef161fbaf48a0e10fca90ef5290a062462b307b3898aa562993853b9f80a  internal/cbm/vendored/grammars/swift/tree_sitter/parser.h
diff --git a/tests/test_extraction.c b/tests/test_extraction.c
index 5b8d16f61..cb7a1a8c8 100644
--- a/tests/test_extraction.c
+++ b/tests/test_extraction.c
@@ -1810,6 +1810,24 @@ TEST(swift_chained_call) {
     PASS();
 }
 
+/* A Swift force-unwrap is the one thing that reaches the scanner's suppressor
+ * path -- the rule that stops `try!` emitting its `!` as a token of its own.
+ * That path shifted an int by up to TOKEN_COUNT bits, which runs past the
+ * width of the type once the index reaches 31.
+ *
+ * This test cannot go red here. The normal test build prints the UBSan
+ * message and carries on, which is why the bug survived. The Windows
+ * CLANGARM64 leg runs UBSan in trap mode, where the same shift is an
+ * illegal-instruction crash, so parsing this file at all is the check. */
+TEST(swift_force_unwrap_scanner_shift) {
+    CBMFileResult *r =
+        extract("func load() { let u = cached! }\n", CBM_LANG_SWIFT, "t", "Load.swift");
+    ASSERT_NOT_NULL(r);
+    ASSERT_FALSE(r->has_error);
+    cbm_free_result(r);
+    PASS();
+}
+
 /* --- Objective-C --- */
 TEST(objc_interface) {
     CBMFileResult *r =
@@ -6661,6 +6679,7 @@ SUITE(extraction) {
     RUN_TEST(swift_method_call);
     RUN_TEST(swift_constructor_call);
     RUN_TEST(swift_chained_call);
+    RUN_TEST(swift_force_unwrap_scanner_shift);
     RUN_TEST(objc_interface);
     RUN_TEST(objc_implementation);
     RUN_TEST(dart_top_level_function);