diff --git a/components/style/values/specified/box.rs b/components/style/values/specified/box.rs
index 5f34ef91884..afa88955d98 100644
--- a/components/style/values/specified/box.rs
+++ b/components/style/values/specified/box.rs
@@ -999,10 +999,10 @@ pub enum Appearance {
     /// A scrollbar button (up/down/left/right).
     /// Keep these in order (some code casts these values to `int` in order to
     /// compare them against each other).
+    ScrollbarbuttonUp,
     ScrollbarbuttonDown,
     ScrollbarbuttonLeft,
     ScrollbarbuttonRight,
-    ScrollbarbuttonUp,
     /// The scrollbar thumb.
     ScrollbarthumbHorizontal,
     ScrollbarthumbVertical,