diff --git a/doc/source/conf.py b/doc/source/conf.py
index 1472a694..75af76fb 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -367,7 +367,7 @@ def setup(app):
 
 # plot_directive options
 plot_include_source = True
-plot_formats = [('png', 96), 'pdf']
+plot_formats = [('png', 96)]
 plot_html_show_formats = False
 plot_html_show_source_link = False