diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 7a670e6d27c6a17c431d5521302bb4bfe7700f29..bca215d77c5ddc852ee346349d530d1c28954aeb 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -5,6 +5,7 @@ stages:
 
 variables:
   CPU_CORES: "10"
+  OCAML: "ocaml-base-compiler.4.13.2"
 
 .only_branches: &only_branches
   only: