diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index ac8390074f4c82a6c40960a892a69e4c871eaf1e..9bd558c7d0e307bbcfd3e6720cf60b718a248067 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,4 +1,5 @@
 # This file is generated by GitLab CI
+image: ruby:2.2
 before_script:
   - ./scripts/prepare_build.sh
   - ruby -v