diff --git a/js/jsd/jsd_obj.c b/js/jsd/jsd_obj.c
index 00a5d8c77a3f..9a9abe5154cb 100644
--- a/js/jsd/jsd_obj.c
+++ b/js/jsd/jsd_obj.c
@@ -140,6 +140,7 @@ jsd_Constructing(JSDContext* jsdc, JSContext *cx, JSObject *obj,
     JSScript* script;
     JSDScript* jsdscript;
     const char* ctorURL;
+    JSString* ctorNameStr;
     const char* ctorName;
 
     JSD_LOCK_OBJECTS(jsdc);
@@ -156,11 +157,11 @@ jsd_Constructing(JSDContext* jsdc, JSContext *cx, JSObject *obj,
             JSD_LOCK_SCRIPTS(jsdc);
             jsdscript = jsd_FindOrCreateJSDScript(jsdc, cx, script, fp);
             JSD_UNLOCK_SCRIPTS(jsdc);
-            if( jsdscript )
-            {
-                ctorName = jsd_GetScriptFunctionId(jsdc, jsdscript);
-                if( ctorName )
+            if( jsdscript && (ctorNameStr = jsd_GetScriptFunctionId(jsdc, jsdscript)) ) {
+                if( (ctorName = JS_EncodeString(cx, ctorNameStr)) ) {
                     jsdobj->ctorName = jsd_AddAtom(jsdc, ctorName);
+                    JS_free(cx, (void *) ctorName);
+                }
             }
             jsdobj->ctorLineno = JS_GetScriptBaseLineNumber(cx, script);
         }