diff --git a/.travis.yml b/.travis.yml
index 36b1604..44641af 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,8 +1,8 @@
 language: php
 
 php:
-  - 7.0
-  - 7.2
+  - '7.0'
+  - '7.2'
 
 git:
   depth: 10