--- a/layout/base/nsDisplayList.h
+++ b/layout/base/nsDisplayList.h
@@ -1346,16 +1346,17 @@ public:
    * temporary items.
    */
   explicit nsDisplayItem(nsIFrame* aFrame)
     : mFrame(aFrame)
     , mClip(nullptr)
     , mScrollClip(nullptr)
     , mReferenceFrame(nullptr)
     , mAnimatedGeometryRoot(nullptr)
+    , mForceNotVisible(false)
 #ifdef MOZ_DUMP_PAINTING
     , mPainted(false)
 #endif
   {
   }
   virtual ~nsDisplayItem() {}
 
   void* operator new(size_t aSize,