diff --git a/docs/source/conf.py b/docs/source/conf.py
index 38e76a1..a5ccad8 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -63,7 +63,7 @@
 templates_path = []#['./_templates']
 
 # mock imports for autodoc
-autodoc_mock_imports = ["webbpsf"]
+autodoc_mock_imports = ["webbpsf", "webbpsf-ext"]
 
 
 # nbsphinx settings