diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index d92ae57fbf923b0b0fedfe5728ed1f62013eae56..99a7292367a8232ebe8b5db47df23696b6359b90 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.8.15.1:
   <<: *template