diff --git a/requirements.txt b/requirements.txt
index 5ac0b37..08d22f4 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,5 +1,6 @@
 bumpversion
 ipython
+mkdocs<=1.0.4
 nbsphinx==0.3.2
 pre-commit
 pytest