diff --git a/dom/base/nsNodeUtils.cpp b/dom/base/nsNodeUtils.cpp
index 9c1f757fcd..8806773a44 100644
--- a/dom/base/nsNodeUtils.cpp
+++ b/dom/base/nsNodeUtils.cpp
@@ -471,8 +471,14 @@ nsNodeUtils::CloneAndAdopt(nsINode *aNode, bool aClone, bool aDeep,
         JSAutoCompartment ac(cx, wrapper);
         rv = ReparentWrapper(cx, wrapper);
         if (NS_FAILED(rv)) {
+          if (wasRegistered) {
+            aNode->OwnerDoc()->UnregisterActivityObserver(aNode->AsElement());
+          }
           aNode->mNodeInfo.swap(newNodeInfo);
 
+          if (wasRegistered) {
+            aNode->OwnerDoc()->RegisterActivityObserver(aNode->AsElement());
+          }
           return rv;
         }
       }