diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index a36ad110abf91b17e62d00805f1e4dd14a71818a..f1c888e4fd5a56e9e2f34b556b95cb1afd38bd4d 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -435,7 +435,7 @@ hadrian-multi:
     # workaround for docker permissions
     - sudo chown ghc:ghc -R .
   variables:
-    GHC_FLAGS: "-Werror -Wwarn=deprecations"
+    GHC_FLAGS: "-Werror -Wwarn=deprecations -Wwarn=unused-imports"
     CONFIGURE_ARGS: --enable-bootstrap-with-devel-snapshot
   tags:
     - x86_64-linux