diff --git a/docs/notebook_requirements.txt b/docs/notebook_requirements.txt
index af065bce..e941351a 100644
--- a/docs/notebook_requirements.txt
+++ b/docs/notebook_requirements.txt
@@ -27,6 +27,7 @@ numpy==1.15.2
 pandas==0.23.4
 pandocfilters==1.4.2
 parso==0.3.1
+patsy==0.5.0
 pexpect==4.6.0
 pickleshare==0.7.4
 prometheus-client==0.3.0