diff --git a/MANUAL.txt b/MANUAL.txt
index 9ffc44db8..958a95593 100644
--- a/MANUAL.txt
+++ b/MANUAL.txt
@@ -4168,6 +4168,8 @@ ordered list marker in place of a numeral:
     #. one
     #. two
 
+Note:  the '`#`' ordered list marker doesn't work with `commonmark`.
+
 #### Extension: `startnum` ####
 
 Pandoc also pays attention to the type of list marker used, and to the