diff --git a/layout/style/nsCSSPropList.h b/layout/style/nsCSSPropList.h
index 44bd44cef4..f62aa38272 100644
--- a/layout/style/nsCSSPropList.h
+++ b/layout/style/nsCSSPropList.h
@@ -470,6 +470,7 @@ CSS_PROP_DISPLAY(
     kAppearanceKTable,
     CSS_PROP_NO_OFFSET,
     eStyleAnimType_Discrete)
+#ifndef CSS_PROP_LIST_EXCLUDE_INTERNAL
 CSS_PROP_POSITION(
     aspect-ratio,
     aspect_ratio,
@@ -481,6 +482,7 @@ CSS_PROP_POSITION(
     nullptr,
     offsetof(nsStylePosition, mAspectRatio),
     eStyleAnimType_None)
+#endif // CSS_PROP_LIST_EXCLUDE_INTERNAL
 CSS_PROP_DISPLAY(
     backface-visibility,
     backface_visibility,