diff --git a/source/conf.py b/source/conf.py
index b4527241d..33fd5868e 100644
--- a/source/conf.py
+++ b/source/conf.py
@@ -86,7 +86,7 @@ class copyAllConsole (BashSessionLexer):
 #
 # 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'
 
 # There are two options for replacing |today|: either, you set today to some
 # non-false value, then it is used: