--- a/gfx/layers/wr/WebRenderLayerManager.cpp
+++ b/gfx/layers/wr/WebRenderLayerManager.cpp
@@ -536,20 +536,17 @@ WebRenderLayerManager::GenerateFallbackD
       PixelCastJustification::WebRenderHasUnitResolution);
 
   LayerIntSize imageSize = RoundedToInt(bounds.Size());
   aImageRect = LayerRect(LayerPoint(0, 0), LayerSize(imageSize));
   if (imageSize.width == 0 || imageSize.height == 0) {
     return nullptr;
   }
 
-  aOffset = ViewAs<LayerPixel>(
-      LayoutDevicePoint::FromAppUnits(clippedBounds.TopLeft(), appUnitsPerDevPixel),
-      PixelCastJustification::WebRenderHasUnitResolution);
-
+  aOffset = RoundedToInt(bounds.TopLeft());
   nsRegion invalidRegion;
   nsAutoPtr<nsDisplayItemGeometry> geometry = fallbackData->GetGeometry();
 
   if (geometry) {
     nsRect invalid;
     if (aItem->IsInvalid(invalid)) {
       invalidRegion.OrWith(clippedBounds);
     } else {