diff --git a/examples/client.rs b/examples/client.rs
index 00e36074..c3b505d9 100644
--- a/examples/client.rs
+++ b/examples/client.rs
@@ -1,4 +1,4 @@
-#![feature(env)]
+#![deny(warnings)]
 extern crate hyper;
 
 use std::env;
diff --git a/examples/hello.rs b/examples/hello.rs
index 9cb12929..f9bb03ca 100644
--- a/examples/hello.rs
+++ b/examples/hello.rs
@@ -1,3 +1,4 @@
+#![deny(warnings)]
 #![feature(io, net)]
 extern crate hyper;
 
diff --git a/examples/server.rs b/examples/server.rs
index 8b110dbd..06d37596 100644
--- a/examples/server.rs
+++ b/examples/server.rs
@@ -1,3 +1,4 @@
+#![deny(warnings)]
 #![feature(io, net)]
 extern crate hyper;
 #[macro_use] extern crate log;