diff --git a/debian/gitlab-ci.yml b/debian/gitlab-ci.yml
index e59c777ed447603202fbfbad324551a2ab3a9364..a3e367ecbfbb2a115eadb400a20644f83db92718 100644
--- a/debian/gitlab-ci.yml
+++ b/debian/gitlab-ci.yml
@@ -56,6 +56,7 @@ ubsan:
             meson \
                 -Db_lundef=false \
                 -Db_sanitize=address,undefined \
+                --werror \
                 builddir
             ninja -C builddir scan-build
             meson test -C builddir -v