diff --git a/.travis.yml b/.travis.yml
index 8c91a74..ad49a0e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,6 +3,8 @@ rust:
   - stable
   - beta
   - nightly
+env:
+  - RUSTFLAGS="-D warnings"
 matrix:
   allow_failures:
     - rust: nightly