diff --git a/layout/style/nsStyleStruct.h b/layout/style/nsStyleStruct.h
index 1c6e2b5a3d4a0ca2b5ef50a84c220958885ce3e3..d74f5558ab70c53fc2649f0f3ab40a456c3e1c6a 100644
--- a/layout/style/nsStyleStruct.h
+++ b/layout/style/nsStyleStruct.h
@@ -2003,6 +2003,7 @@ 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
