diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 13bc283c77c88eead0b0297c5069e468205ce552..efcb890979b542aa0617abe8f07122d05dcd16b1 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,3 +1,5 @@
+image: ruby:2.2
+
 build:
   stage: build
   script: