diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index b25bb93..5c8d9d8 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -4065,6 +4065,7 @@
 		customlist,{func} custom completion, defined via {func}
 		diff_buffer     |:diffget| and |:diffput| completion
 		dir		directory names
+		dir_in_path	directory names in |'cdpath'|
 		environment	environment variable names
 		event		autocommand events
 		expression	Vim expression