diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 34b597969b7b0ac464bc046798e0438184c6e44f..6ec6cb5fb3e43b3b271fda9629dd3b2e7c13376e 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -62,7 +62,7 @@ test-centos7:
   - coverage html
   - pip3.6 install sphinx sphinx-argparse sphinxcontrib.bibtex sphinx_rtd_theme
   - cd docs
-  - make html
+  - PYTHON=python3.6 make html
   artifacts:
     paths:
       - ippisite/htmlcov
diff --git a/ippisite/docs/Makefile b/ippisite/docs/Makefile
index 5fa94b06cfe70549942f3160cd249d19590d194b..2d45653d881621ef72b0461f44d29827e85f416f 100644
--- a/ippisite/docs/Makefile
+++ b/ippisite/docs/Makefile
@@ -19,5 +19,5 @@ help:
 # "make mode" option.  $(O) is meant as a shortcut for $(SPHINXOPTS).
 %: Makefile
 	@$(SPHINXAPI) -o $(SOURCEDIR) $(SPHINXAPISRC)
-	python ../manage.py graph_models ippidb --dot > source/db.dot
+	$(PYTHON) ../manage.py graph_models ippidb --dot > source/db.dot
 	@$(SPHINXBUILD) -M $@ "$(SOURCEDIR)" "$(BUILDDIR)" $(SPHINXOPTS) $(O)