diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index a6af088ba9346f86be603a10c7ed161458a0b86c..26d36bf38bbecea2461e0db04f3b57016bc1bf8b 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -124,7 +124,9 @@ pages:
   only:
     - tags
     - master
+    - doc_on_gitlab-pages
   script:
+    - pyenv shell 3.6.4  # black install needs python 3.6.x minimum
     - pip install -r requirements.txt
     - pip install -r requirements_dev.txt
     - make docs