diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index bb71cfd376a94c82911bfa7da4116b81a78dcb22..34a57f47f2e87c33d1f72c4459cd094d111bf581 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,4 +1,4 @@
-image: python:3.8-buster
+image: python:3.9-bullseye
 
 variables:
   GIT_SUBMODULE_STRATEGY: recursive
@@ -7,6 +7,7 @@ variables:
 pages:
   stage: deploy
   before_script:
+  - apt update; apt install po4a
   - pip install -r requirements.txt
   script:
   - make publish; make publish