diff --git a/components/style/properties/longhands/ui.mako.rs b/components/style/properties/longhands/ui.mako.rs
index 1111fdb7253..d006ff0b9a6 100644
--- a/components/style/properties/longhands/ui.mako.rs
+++ b/components/style/properties/longhands/ui.mako.rs
@@ -51,12 +51,15 @@ ${helpers.single_keyword(
     spec="None (Nonstandard Firefox-only property)",
 )}
 
+// TODO(emilio): Maybe make shadow behavior on macOS match Linux / Windows, and remove this
+// property.
 ${helpers.single_keyword(
     "-moz-window-shadow",
-    "default none menu tooltip sheet cliprounded",
+    "default none",
     engines="gecko",
     gecko_ffi_name="mWindowShadow",
     gecko_enum_prefix="StyleWindowShadow",
+    gecko_inexhaustive=True,
     animation_value_type="discrete",
     enabled_in="chrome",
     spec="None (Nonstandard internal property)",