--- a/tools/profiler/JSObjectBuilder.h
+++ b/tools/profiler/JSObjectBuilder.h
@@ -51,17 +51,17 @@ class JSObjectBuilder
     mOk = JS_DefineProperty(mCx, aObject, name, STRING_TO_JSVAL(string), NULL, NULL, JSPROP_ENUMERATE);
   }
 
   void DefineProperty(JSObject *aObject, const char *name, const char *value, size_t valueLength)
   {
     if (!mOk)
       return;
 
-    JSString *string = JS_NewStringCopyN(mCx, value, valueLength);
+    JSString *string = JS_InternStringN(mCx, value, valueLength);
     if (!string) {
       mOk = JS_FALSE;
       return;
     }
 
     mOk = JS_DefineProperty(mCx, aObject, name, STRING_TO_JSVAL(string), NULL, NULL, JSPROP_ENUMERATE);
   }