diff --git a/man2/mkdir.2 b/man2/mkdir.2
index a5c0871ed..d517603b4 100644
--- a/man2/mkdir.2
+++ b/man2/mkdir.2
@@ -57,7 +57,7 @@ It is modified by the process's
 .I umask
 in the usual way: in the absence of a default ACL, the mode of the
 created directory is
-.RI ( mode " & ~" umask " & 0777)."
+.RI ( mode " & ~" umask " & 01777)."
 Other mode bits of the created directory depend on the operating system.
 For Linux, see below.