diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 939450e931f38d07afd7b99b451b1c9ae2c147f9..4e9f9e6c366ee06b9d3219eb235ad348c8c49904 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -36,5 +36,5 @@ static:
   tags: [ pyFstat ]
   script:
     - source ${VENV_DIR}/bin/activate
-    - black --check .
+    - black --check --diff .
     # - flake8 .  ## not ready