diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 6f9b783d8d06bbb079f672030442991bf2e5f83a..ce239483a8951eca6dc44516f81150773696e638 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -46,6 +46,7 @@ build-coq.8.16.dev:
   <<: *template
   variables:
     OPAM_PINS: "coq version 8.16.dev"
+    DENY_WARNINGS: "1"
 
 build-coq.8.15.0:
   <<: *template