diff --git a/doc/requirements.txt b/doc/requirements.txt
index 202de27045..c8f9a7bfee 100644
--- a/doc/requirements.txt
+++ b/doc/requirements.txt
@@ -27,7 +27,7 @@ pooch
 psutil
 pyarrow
 pyshp==2.1.2
-python-frontmatter
+python-frontmatter==1.1.0
 recommonmark
 requests
 scikit-image==0.20.0