diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 2819d3f760ff9dda6116289ef536ce7a7400bd82..e2fbab7a3a56cda5f53298630471551fc1527bbb 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -61,6 +61,7 @@ test-centos7:
   - coverage run --source='.' manage.py test
   - coverage report
   - coverage html
+  - export LC_CTYPE="en_US.UTF-8"
   - pip3.6 install sphinx==3.5.2 sphinx-argparse==0.2.5 sphinxcontrib.bibtex==2.1.4 sphinx_rtd_theme==0.5.1
   - cd docs
   - PYTHON=python3.6 make html