diff --git a/components/style/lib.rs b/components/style/lib.rs
index a087a1fea5b..b7a7a0ecbab 100644
--- a/components/style/lib.rs
+++ b/components/style/lib.rs
@@ -23,7 +23,7 @@
 //! [cssparser]: ../cssparser/index.html
 //! [selectors]: ../selectors/index.html
 
-// #![deny(warnings)]
+#![deny(warnings)]
 #![deny(missing_docs)]
 
 // FIXME(bholley): We need to blanket-allow unsafe code in order to make the