diff --git a/runtime/doc/various.txt b/runtime/doc/various.txt
index 6f24515..1d21e1a 100644
--- a/runtime/doc/various.txt
+++ b/runtime/doc/various.txt
@@ -249,7 +249,8 @@
 
 							*:!cmd* *:!*
 :!{cmd}			Execute {cmd} with the shell.  See also the 'shell'
-			and 'shelltype' option.
+			and 'shelltype' option. `:!` without a {cmd} is a no-op,
+			it does nothing.
 							*E34*
 			Any '!' in {cmd} is replaced with the previous
 			external command (see also 'cpoptions').  But not when