diff --git a/.travis.yml b/.travis.yml
index 1ffc4f9..69749bb 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -11,8 +11,8 @@ php:
 matrix:
   fast_finish: true
   allow_failures:
-    - php: 5.4
-    - php: 5.5
+    - php: '5.4'
+    - php: '5.5'
     - php: nightly
 
 cache: