--- a/layout/base/nsDisplayList.cpp
+++ b/layout/base/nsDisplayList.cpp
@@ -5083,18 +5083,18 @@ already_AddRefed<Layer>
 nsDisplayFixedPosition::BuildLayer(nsDisplayListBuilder* aBuilder,
                                    LayerManager* aManager,
                                    const ContainerLayerParameters& aContainerParameters) {
   RefPtr<Layer> layer =
     nsDisplayOwnLayer::BuildLayer(aBuilder, aManager, aContainerParameters);
 
   layer->SetIsFixedPosition(true);
 
-  nsPresContext* presContext = Frame()->PresContext();
-  nsIFrame* fixedFrame = mIsFixedBackground ? presContext->PresShell()->GetRootFrame() : Frame();
+  nsPresContext* presContext = mFrame->PresContext();
+  nsIFrame* fixedFrame = mIsFixedBackground ? presContext->PresShell()->GetRootFrame() : mFrame;
 
   const nsIFrame* viewportFrame = fixedFrame->GetParent();
   // anchorRect will be in the container's coordinate system (aLayer's parent layer).
   // This is the same as the display items' reference frame.
   nsRect anchorRect;
   if (viewportFrame) {
     // Fixed position frames are reflowed into the scroll-port size if one has
     // been set.