diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index e57de8f..8a106e1 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -7339,7 +7339,7 @@
 
 	After this option has been set successfully, Vim will source the files
 	"spell/LANG.vim" in 'runtimepath'.  "LANG" is the value of 'spelllang'
-	up to the first comma, dot or underscore.
+	up to the first character that is not an ASCII letter and not a dash.
 	Also see |set-spc-auto|.