diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index b3d728596f00e85b395e5bf8e7fc0c0cd79c4736..792ab22f1524f8d4dc1db90f2b65c7f8f28f90ed 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -73,6 +73,8 @@ unittest_py3.9:
   stage: test
   needs: [ ]
   script:
+    # verify that this actually is Python 3.9
+    - python3 -c "import sys; assert sys.version.startswith('3.9')"
     - touch ~/.pycaosdb.ini
     - make unittest