diff --git a/docs/requirements.txt b/docs/requirements.txt
index b92fe55..ea7c67f 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -5,3 +5,4 @@ numpydoc>=0.9.1
 sphinx_bootstrap_theme>=0.7.1
 PyQt5~=5.13.0
 zarr
+mock