--- a/gfx/webrender_bindings/WebRenderTypes.h
+++ b/gfx/webrender_bindings/WebRenderTypes.h
@@ -320,16 +320,17 @@ static inline wr::LayoutSize ToLayoutSiz
 static inline wr::ComplexClipRegion ToComplexClipRegion(const RoundedRect& rect)
 {
   wr::ComplexClipRegion ret;
   ret.rect               = ToLayoutRect(rect.rect);
   ret.radii.top_left     = ToLayoutSize(LayoutDeviceSize::FromUnknownSize(rect.corners.radii[mozilla::eCornerTopLeft]));
   ret.radii.top_right    = ToLayoutSize(LayoutDeviceSize::FromUnknownSize(rect.corners.radii[mozilla::eCornerTopRight]));
   ret.radii.bottom_left  = ToLayoutSize(LayoutDeviceSize::FromUnknownSize(rect.corners.radii[mozilla::eCornerBottomLeft]));
   ret.radii.bottom_right = ToLayoutSize(LayoutDeviceSize::FromUnknownSize(rect.corners.radii[mozilla::eCornerBottomRight]));
+  ret.mode = wr::ClipMode::Clip;
   return ret;
 }
 
 static inline wr::LayoutSize ToLayoutSize(const mozilla::LayoutDeviceIntSize& size)
 {
   return ToLayoutSize(LayoutDeviceSize(size));
 }
 

--- a/layout/painting/DisplayItemClip.cpp
+++ b/layout/painting/DisplayItemClip.cpp
@@ -485,12 +485,13 @@ DisplayItemClip::ToComplexClipRegions(in
     region->rect = aSc.ToRelativeLayoutRect(LayoutDeviceRect::FromAppUnits(
         mRoundedClipRects[i].mRect, aAppUnitsPerDevPixel));
     const nscoord* radii = mRoundedClipRects[i].mRadii;
     region->radii = wr::ToBorderRadius(
         LayoutDeviceSize::FromAppUnits(nsSize(radii[eCornerTopLeftX], radii[eCornerTopLeftY]), aAppUnitsPerDevPixel),
         LayoutDeviceSize::FromAppUnits(nsSize(radii[eCornerTopRightX], radii[eCornerTopRightY]), aAppUnitsPerDevPixel),
         LayoutDeviceSize::FromAppUnits(nsSize(radii[eCornerBottomLeftX], radii[eCornerBottomLeftY]), aAppUnitsPerDevPixel),
         LayoutDeviceSize::FromAppUnits(nsSize(radii[eCornerBottomRightX], radii[eCornerBottomRightY]), aAppUnitsPerDevPixel));
+    region->mode = wr::ClipMode::Clip;
   }
 }
 
 } // namespace mozilla