--- a/gfx/layers/wr/StackingContextHelper.cpp
+++ b/gfx/layers/wr/StackingContextHelper.cpp
@@ -74,17 +74,17 @@ StackingContextHelper::StackingContextHe
                                              float* aOpacityPtr,
                                              gfx::Matrix4x4* aTransformPtr,
                                              gfx::Matrix4x4* aPerspectivePtr,
                                              const nsTArray<wr::WrFilterOp>& aFilters,
                                              const gfx::CompositionOp& aMixBlendMode)
   : mBuilder(&aBuilder)
 {
   nsRect visibleRect;
-  bool is2d = aTransformPtr && aTransformPtr->Is2D() && !aPerspectivePtr;
+  bool is2d = !aTransformPtr || (aTransformPtr->Is2D() && !aPerspectivePtr);
   if (is2d) {
     nsRect itemBounds = aDisplayList->GetClippedBoundsWithRespectToASR(aDisplayListBuilder, aItem->GetActiveScrolledRoot());
     nsRect childrenVisible = aItem->GetVisibleRectForChildren();
     visibleRect = itemBounds.Intersect(childrenVisible);
   } else {
     visibleRect = aDisplayList->GetBounds(aDisplayListBuilder);
     // The position of bounds are calculated by transform and perspective matrix in 3d case. reset it to (0, 0)
     visibleRect.MoveTo(0, 0);