diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 06bde42149ea160227673764f3910fdc649c3c53..12c1cb1db0006d8a594fd99d1062c9d2fd680db6 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,4 +1,6 @@
-image: ruby:latest
+# ruby:2.6.4 (ruby:latest at time of writing has bundle version 1.17.2, which is too old)
+#image: ruby:latest
+image: ruby:rc
 
 variables:
   JEKYLL_ENV: production