diff --git a/releasenotes/source/conf.py b/releasenotes/source/conf.py
index b681cc9..cdcdfbd 100644
--- a/releasenotes/source/conf.py
+++ b/releasenotes/source/conf.py
@@ -86,7 +86,7 @@ release = ''
 #
 # This is also used if you do content translation via gettext catalogs.
 # Usually you set "language" from the command line for these cases.
-language = None
+language = "en"
 
 # List of patterns, relative to source directory, that match files and
 # directories to ignore when looking for source files.