diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index cf37387..d8f4dfb 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -3976,7 +3976,9 @@
 	The highlighting can be set with the 'i' flag in 'highlight'.
 	See also: 'hlsearch'.
 	CTRL-L can be used to add one character from after the current match
-	to the command line.
+	to the command line.  If 'ignorecase' and 'smartcase' are set and the
+	command line has no uppercase characters, the added character is
+	converted to lowercase.
 	CTRL-R CTRL-W can be used to add the word at the end of the current
 	match, excluding the characters that were already typed.
 	NOTE: This option is reset when 'compatible' is set.