diff --git a/src/java_lang_String.cc b/src/java_lang_String.cc
index 9aa5221..fbabd43 100644
--- a/src/java_lang_String.cc
+++ b/src/java_lang_String.cc
@@ -148,8 +148,8 @@
 }
 
 jstring String_intern(JNIEnv* env, jobject javaThis) {
-  String* s = Decode<String*>(env, javaThis);
-  String* result = s->Intern();
+  const String* s = Decode<String*>(env, javaThis);
+  const String* result = s->Intern();
   return AddLocalReference<jstring>(env, result);
 }