diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 6a33db667831a41fbe32e110317ce4e7ae1f96ff..c5c76ac355545a2697924424c7d9903ee2edd6ec 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -6,7 +6,7 @@ pages:
   script:
   - apt-get update
   - apt-get install --assume-yes pandoc
-  - pip install numpy pandas termcolor paho-mqtt  # top import of Ohmpi.py
+  - pip install numpy pandas termcolor paho-mqtt zmq  # top import of Ohmpi.py
   - pip install sphinx numpydoc sphinx_rtd_theme pandoc recommonmark
   - cd doc
   - make html