diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 75d7aa959c3147e0b2970413d20b10b527ba1676..67624c61b18e99ce91d2f12eabef2047e800862d 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -79,6 +79,7 @@ unit-test-job:   # This job runs in the test stage.
 pages:
   stage: deploy
   script:
+  - apt update
   - apt-get install graphviz
   - pip install -U sphinx m2r2 furo graphviz pyUML pydot gprof2dot
   - pip install -e .