diff --git a/layout/style/nsStyleStruct.h b/layout/style/nsStyleStruct.h
index 4811ceab129cd2dcbc65de52c2978bc5735aa486..8ed6eb405cf8843811d8d9721532ab646dc2d759 100644
--- a/layout/style/nsStyleStruct.h
+++ b/layout/style/nsStyleStruct.h
@@ -2026,6 +2026,7 @@ 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
