diff --git a/layout/painting/nsDisplayList.h b/layout/painting/nsDisplayList.h
index 0c81af30ffef..621ef342f36b 100644
--- a/layout/painting/nsDisplayList.h
+++ b/layout/painting/nsDisplayList.h
@@ -3824,7 +3824,8 @@ public:
   nsDisplayTableBackgroundImage(const InitData& aInitData, nsIFrame* aCellFrame);
 
   virtual uint32_t GetPerFrameKey() const override {
-    return (static_cast<uint8_t>(mTableType) << TYPE_BITS) |
+    return (mLayer << (TYPE_BITS + static_cast<uint8_t>(TableTypeBits::COUNT))) |
+           (static_cast<uint8_t>(mTableType) << TYPE_BITS) |
            nsDisplayItem::GetPerFrameKey();
   }