diff --git a/components/style_derive/to_css.rs b/components/style_derive/to_css.rs
index 1d3a2f2d230..4f8841810c1 100644
--- a/components/style_derive/to_css.rs
+++ b/components/style_derive/to_css.rs
@@ -5,16 +5,12 @@
 use cg;
 use darling::util::Override;
 use quote::{ToTokens, Tokens};
-use syn::{self, Data, GenericParam, Path, WhereClause};
+use syn::{self, Data, Path, WhereClause};
 use synstructure::{BindingInfo, Structure, VariantInfo};
 
 pub fn derive(mut input: syn::DeriveInput) -> Tokens {
     let mut where_clause = input.generics.where_clause.take();
-    for param in &input.generics.params {
-        let param = match *param {
-            GenericParam::Type(ref param) => param,
-            _ => continue,
-        };
+    for param in input.generics.type_params() {
         cg::add_predicate(
             &mut where_clause,
             parse_quote!(#param: ::style_traits::ToCss),