diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 2a63ee15af0bfc70c8abf2572bd5b443d6d03a78..e8d54e768d3095fbb89966db95c8c7e1a7fc3443 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,7 +1,7 @@
-image: "ruby:2.3"
+image: "ruby:2.3.1"
 
 cache:
-  key: "ruby-23"
+  key: "ruby-231"
   paths:
   - vendor/apt
   - vendor/ruby