diff --git a/layout/style/nsStyleStruct.h b/layout/style/nsStyleStruct.h
index 3236244280edaae2bbe4440e76da3455015ab722..3474d4bcfab2944aae9635250350b674a8ed1c42 100644
--- a/layout/style/nsStyleStruct.h
+++ b/layout/style/nsStyleStruct.h
@@ -2033,6 +2033,7 @@ struct MOZ_NEEDS_MEMMOVABLE_MEMBERS nsStyleUIReset {
   // The margin of the window region that should be transparent to events.
   mozilla::StyleLength mMozWindowInputRegionMargin;
   mozilla::StyleTransform mMozWindowTransform;
+  mozilla::StyleTransformOrigin mWindowTransformOrigin;
 
   nsStyleAutoArray<mozilla::StyleTransition> mTransitions;
   // The number of elements in mTransitions that are not from repeating
