diff --git a/components/style/properties/properties.mako.rs b/components/style/properties/properties.mako.rs
index f4d303f9eb8..95d59df064d 100644
--- a/components/style/properties/properties.mako.rs
+++ b/components/style/properties/properties.mako.rs
@@ -2592,8 +2592,11 @@ impl SourcePropertyDeclaration {
 
 /// Return type of SourcePropertyDeclaration::drain
 pub struct SourcePropertyDeclarationDrain<'a> {
-    declarations: ArrayVecDrain<'a, PropertyDeclaration, ${max(len(s.sub_properties) for s in data.shorthands_except_all()) \
-          if data.shorthands_except_all() else 0}>,
+    declarations: ArrayVecDrain<
+        'a, PropertyDeclaration,
+        ${max(len(s.sub_properties) for s in data.shorthands_except_all()) \
+            if data.shorthands_except_all() else 0}
+    >,
     all_shorthand: AllShorthand,
 }