diff --git a/.travis.yml b/.travis.yml
index 47f3424df2f..183409acd46 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -15,7 +15,7 @@ build: &rust_build
         - cargo gen-syntax --verify
         - cargo test
     env:
-        RUSTFLAGS: "-D warnings"
+        - RUSTFLAGS="-D warnings"
 
 matrix:
     include: