diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index b1f3e15..38eb31d 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -3633,7 +3633,8 @@
 	one dot may appear.
 	This option is not copied to another buffer, independent of the 's' or
 	'S' flag in 'cpoptions'.
-	Only alphanumeric characters, '-' and '_' can be used.
+	Only alphanumeric characters, '-' and '_' can be used (and a '.' is 
+	allowed as delimiter when combining different filetypes).
 
 						*'fillchars'* *'fcs'*
 'fillchars' 'fcs'	string	(default "vert:|,fold:-,eob:~,lastline:@")