diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index ec10889..b7df7c5 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -7588,7 +7588,7 @@
 		the new directory.  The default is 0o755 (rwxr-xr-x: r/w for
 		the user, readable for others).  Use 0o700 to make it
 		unreadable for others.  This is used for the newly created
-		directories.  Note an umask is applied to {prot} (on Unix).
+		directories.  Note: umask is applied to {prot} (on Unix).
 		Example: >
 			:call mkdir($HOME .. "/tmp/foo/bar", "p", 0o700)