diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 1d8b132d1ec458207b1f6bdb62a4521081ee1762..0801de8a3b31c748861bc92df20a3eb21bfafe54 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,3 +1,5 @@
+image: ruby:2.3.1
+
 services:
   - postgres:9.5
   - elasticsearch:2