diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 66236a8dfe40292c15ea49b20f455ddec586ae9b..44a7f57e20b980bdf4f8bbaa01e7641282bbdcc2 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,3 +1,4 @@
 doctests and unitests:
+    image: python:3.6
     script: pip install pytest
             pytest --doctest-modules -v --ignore=GUIs
\ No newline at end of file