diff --git a/mozilla/dom/src/base/nsDOMClassInfo.cpp b/mozilla/dom/src/base/nsDOMClassInfo.cpp
index 5d72c9fc4cf..4ae6f14d650 100644
--- a/mozilla/dom/src/base/nsDOMClassInfo.cpp
+++ b/mozilla/dom/src/base/nsDOMClassInfo.cpp
@@ -6701,9 +6701,10 @@ nsEventReceiverSH::NewResolve(nsIXPConnectWrappedNative *wrapper,
 
   if (id == sAddEventListener_id && !(flags & JSRESOLVE_ASSIGNING)) {
     JSString *str = JSVAL_TO_STRING(id);
+    // addEventListener always takes at leat 3 arguments.
     JSFunction *fnc =
       ::JS_DefineFunction(cx, obj, ::JS_GetStringBytes(str),
-                          AddEventListenerHelper, 0, JSPROP_ENUMERATE);
+                          AddEventListenerHelper, 3, JSPROP_ENUMERATE);
 
     *objp = obj;