diff --git a/utils/src/main/java/datadog/instrument/utils/ClassNameTrie.java b/utils/src/main/java/datadog/instrument/utils/ClassNameTrie.java
index dc1bccf..5e3f617 100644
--- a/utils/src/main/java/datadog/instrument/utils/ClassNameTrie.java
+++ b/utils/src/main/java/datadog/instrument/utils/ClassNameTrie.java
@@ -1058,6 +1058,9 @@ public static boolean generateJavaTrie(
       int chunkSize = 0;
       StringBuilder buf = new StringBuilder();
       buf.append("      \"");
+      if (trie.isEmpty()) {
+        buf.append("\\000"); // encode an empty root node with zero branches
+      }
       for (int i = 0; i < trie.trieLength; i++) {
         char c = trie.trieData[i];
         if (++chunkSize > 10_000) {
diff --git a/utils/src/test/java/datadog/instrument/utils/ClassNameTrieTest.java b/utils/src/test/java/datadog/instrument/utils/ClassNameTrieTest.java
index 722202c..43e48be 100644
--- a/utils/src/test/java/datadog/instrument/utils/ClassNameTrieTest.java
+++ b/utils/src/test/java/datadog/instrument/utils/ClassNameTrieTest.java
@@ -166,6 +166,28 @@ void generateJavaSource(@TempDir File classesDir) throws Exception {
     assertEquals(5, trieApply.invoke(null, "com.foobar.Five"));
   }
 
+  @Test
+  void generateEmptyJavaSource(@TempDir File classesDir) throws Exception {
+    Files.createFile(new File(classesDir, "empty.trie").toPath());
+    ClassNameTrie.JavaGenerator.main(
+        new String[] {classesDir.toString(), classesDir.toString(), "empty.trie"});
+
+    assertEquals(
+        0,
+        getSystemJavaCompiler()
+            .run(null, null, null, new File(classesDir, "EmptyTrie.java").toString()));
+
+    try (URLClassLoader cl = URLClassLoader.newInstance(new URL[] {classesDir.toURI().toURL()})) {
+      Class<?> trieClass = cl.loadClass("EmptyTrie");
+      Method apply = trieClass.getMethod("apply", String.class);
+      Method applyFromIndex = trieClass.getMethod("apply", String.class, int.class);
+      for (String key : new String[] {"", "a", "com.example.Type"}) {
+        assertEquals(-1, apply.invoke(null, key));
+        assertEquals(-1, applyFromIndex.invoke(null, "prefix/" + key, 7));
+      }
+    }
+  }
+
   @Test
   @SuppressWarnings("UnnecessaryUnicodeEscape")
   void manual() throws IOException {