1 files changed, 2 insertions, 1 deletions
diff --git a/dom/bindings/CallbackObject.h b/dom/bindings/CallbackObject.h
index 8a3d45dfc..5cc98fd5d 100644
--- a/dom/bindings/CallbackObject.h
+++ b/dom/bindings/CallbackObject.h
@@ -514,8 +514,9 @@ private:
   {
     // NS_IF_RELEASE because we might have been unlinked before
     nsISupports* ptr = GetISupports();
-    NS_IF_RELEASE(ptr);
+    // Clear mPtrBits before the release to prevent reentrance.
     mPtrBits = 0;
+    NS_IF_RELEASE(ptr);
   }
 
   uintptr_t mPtrBits;