--- a/layout/base/nsDisplayList.cpp
+++ b/layout/base/nsDisplayList.cpp
@@ -2347,16 +2347,30 @@ RegisterThemeGeometry(nsDisplayListBuild
     nsRect borderBox(aFrame->GetOffsetTo(displayRoot), aFrame->GetSize());
     aBuilder->RegisterThemeGeometry(aType,
       LayoutDeviceIntRect::FromUnknownRect(
         borderBox.ToNearestPixels(
           aFrame->PresContext()->AppUnitsPerDevPixel())));
   }
 }
 
+// Return the bounds of the viewport relative to |aFrame|'s reference frame.
+// Returns Nothing() if transforming into |aFrame|'s coordinate space fails.
+static Maybe<nsRect>
+GetViewportRectRelativeToReferenceFrame(nsDisplayListBuilder* aBuilder,
+                                        nsIFrame* aFrame)
+{
+  nsIFrame* rootFrame = aFrame->PresContext()->PresShell()->GetRootFrame();
+  nsRect rootRect = rootFrame->GetRectRelativeToSelf();
+  if (nsLayoutUtils::TransformRect(rootFrame, aFrame, rootRect) == nsLayoutUtils::TRANSFORM_SUCCEEDED) {
+    return Some(rootRect + aBuilder->ToReferenceFrame(aFrame));
+  }
+  return Nothing();
+}
+
 nsDisplayBackgroundImage::nsDisplayBackgroundImage(nsDisplayListBuilder* aBuilder,
                                                    nsIFrame* aFrame,
                                                    uint32_t aLayer,
                                                    const nsRect& aBackgroundRect,
                                                    const nsStyleBackground* aBackgroundStyle)
   : nsDisplayImageContainer(aBuilder, aFrame)
   , mBackgroundStyle(aBackgroundStyle)
   , mBackgroundRect(aBackgroundRect)
@@ -3042,20 +3056,18 @@ nsDisplayBackgroundImage::GetBoundsInter
   nsRect clipRect = mBackgroundRect;
   if (mFrame->GetType() == nsGkAtoms::canvasFrame) {
     nsCanvasFrame* frame = static_cast<nsCanvasFrame*>(mFrame);
     clipRect = frame->CanvasArea() + ToReferenceFrame();
   } else if (nsLayoutUtils::UsesAsyncScrolling(mFrame) && IsNonEmptyFixedImage()) {
     // If this is a background-attachment:fixed image, and APZ is enabled,
     // async scrolling could reveal additional areas of the image, so don't
     // clip it beyond clipping to the document's viewport.
-    nsIFrame* rootFrame = presContext->PresShell()->GetRootFrame();
-    nsRect rootRect = rootFrame->GetRectRelativeToSelf();
-    if (nsLayoutUtils::TransformRect(rootFrame, mFrame, rootRect) == nsLayoutUtils::TRANSFORM_SUCCEEDED) {
-      clipRect = clipRect.Union(rootRect + aBuilder->ToReferenceFrame(mFrame));
+    if (Maybe<nsRect> viewportRect = GetViewportRectRelativeToReferenceFrame(aBuilder, mFrame)) {
+      clipRect = clipRect.Union(*viewportRect);
     }
   }
   const nsStyleImageLayers::Layer& layer = mBackgroundStyle->mImage.mLayers[mLayer];
   return nsCSSRendering::GetBackgroundLayerRect(presContext, mFrame,
                                                 mBackgroundRect, clipRect, layer,
                                                 aBuilder->GetBackgroundPaintFlags());
 }