diff --git a/components/style/properties/longhands/inherited_box.mako.rs b/components/style/properties/longhands/inherited_box.mako.rs
index 1c710dd2ff9..59f28f827af 100644
--- a/components/style/properties/longhands/inherited_box.mako.rs
+++ b/components/style/properties/longhands/inherited_box.mako.rs
@@ -45,6 +45,16 @@ ${helpers.single_keyword(
     servo_restyle_damage="rebuild_and_reflow",
 )}
 
+${helpers.single_keyword(
+    "-moz-box-layout",
+    "legacy flex",
+    engines="gecko",
+    gecko_enum_prefix="StyleMozBoxLayout",
+    animation_value_type="none",
+    enabled_in="chrome",
+    spec="None (internal)",
+)}
+
 ${helpers.single_keyword(
     "text-orientation",
     "mixed upright sideways",