diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 9ff65589b93e41b2d298b43ec24907804d7896fa..c6ee1df6f74814b6fbcc95e9089be4f0df4cce53 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -31,6 +31,7 @@ build-coq.8.11.2:
   <<: *template
   variables:
     OPAM_PINS: "coq version 8.11.2"
+    DENY_WARNINGS: "1"
   tags:
   - fp-timing