diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index fccf483133a02432b01cf74d7ee998e317247a69..bd3ff0be3cf8ec14b244f546fa9be2abc05ab400 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,4 +1,4 @@
-image: ocaml/opam2:ubuntu
+image: ocaml/opam2:ubuntu-18.04
 
 stages:
   - build
@@ -10,7 +10,7 @@ build:
   script:
     - opam repo add verimag-sync-repo "http://www-verimag.imag.fr/DIST-TOOLS/SYNCHRONE/test/opam-repository"
     - eval `opam config env`
-    - sudo opam depext -y lustre-v6 lutin lablgtk3
+    - opam depext -y lustre-v6 lutin lablgtk3
     - opam install -y dune ocamlgraph lutin lablgtk3
     - make
     - make install