diff --git a/docs/requirements.txt b/docs/requirements.txt
index f754bfd..56ebd15 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -3,4 +3,5 @@ ipykernel>=5.1.0
 nbsphinx>=0.4.2
 numpydoc>=0.9.1
 sphinx_bootstrap_theme>=0.7.1
+mock
 PyQt5~=5.13.0