diff --git a/content/xbl/src/nsXBLPrototypeBinding.cpp b/content/xbl/src/nsXBLPrototypeBinding.cpp
index eba7aa5473f..2c74c108d0f 100644
--- a/content/xbl/src/nsXBLPrototypeBinding.cpp
+++ b/content/xbl/src/nsXBLPrototypeBinding.cpp
@@ -1470,6 +1470,28 @@ nsXBLPrototypeBinding::CreateKeyHandlers()
   }
 }
 
+class XBLPrototypeSetupCleanup
+{
+public:
+  XBLPrototypeSetupCleanup(nsXBLDocumentInfo* aDocInfo, const nsACString& aID)
+  : mDocInfo(aDocInfo), mID(aID) {}
+
+  ~XBLPrototypeSetupCleanup()
+  {
+    if (mDocInfo) {
+      mDocInfo->RemovePrototypeBinding(mID);
+    }
+  }
+
+  void Disconnect()
+  {
+    mDocInfo = nsnull;
+  }
+
+  nsXBLDocumentInfo* mDocInfo;
+  nsCAutoString mID;
+};
+
 nsresult
 nsXBLPrototypeBinding::Read(nsIObjectInputStream* aStream,
                             nsXBLDocumentInfo* aDocInfo,
@@ -1554,6 +1576,8 @@ nsXBLPrototypeBinding::Read(nsIObjectInputStream* aStream,
   rv = aDocInfo->SetPrototypeBinding(id, this);
   NS_ENSURE_SUCCESS(rv, rv);
 
+  XBLPrototypeSetupCleanup cleanup(aDocInfo, id);  
+
   nsCAutoString className;
   rv = aStream->ReadCString(className);
   NS_ENSURE_SUCCESS(rv, rv);
@@ -1567,10 +1591,7 @@ nsXBLPrototypeBinding::Read(nsIObjectInputStream* aStream,
     // occurs, the mapping should be removed again so that we don't keep an
     // invalid binding around.
     rv = mImplementation->Read(context, aStream, this, globalObject);
-    if (NS_FAILED(rv)) {
-      aDocInfo->RemovePrototypeBinding(id);
-      return rv;
-    }
+    NS_ENSURE_SUCCESS(rv, rv);
   }
 
   // Next read in the handlers.
@@ -1627,6 +1648,7 @@ nsXBLPrototypeBinding::Read(nsIObjectInputStream* aStream,
     aDocInfo->SetFirstPrototypeBinding(this);
   }
 
+  cleanup.Disconnect();
   return NS_OK;
 }