--- a/dom/base/Element.cpp
+++ b/dom/base/Element.cpp
@@ -1209,17 +1209,17 @@ Element::CreateShadowRoot(ErrorResult& a
 
 already_AddRefed<ShadowRoot>
 Element::AttachShadowInternal(bool aClosed, ErrorResult& aError)
 {
   /**
    * 3. If context object is a shadow host, then throw
    *    an "InvalidStateError" DOMException.
    */
-  if (GetShadowRoot()) {
+  if (GetShadowRoot() || GetXBLBinding()) {
     aError.Throw(NS_ERROR_DOM_INVALID_STATE_ERR);
     return nullptr;
   }
 
   nsAutoScriptBlocker scriptBlocker;
 
   RefPtr<mozilla::dom::NodeInfo> nodeInfo;
   nodeInfo = mNodeInfo->NodeInfoManager()->GetNodeInfo(