diff --git a/sbin/tunefs/tunefs.8 b/sbin/tunefs/tunefs.8
index 065844a831c..caac64b1754 100644
--- a/sbin/tunefs/tunefs.8
+++ b/sbin/tunefs/tunefs.8
@@ -28,7 +28,7 @@
 .\"     @(#)tunefs.8	8.2 (Berkeley) 12/11/93
 .\" $FreeBSD$
 .\"
-.Dd January 29, 2019
+.Dd October 15, 2021
 .Dt TUNEFS 8
 .Os
 .Sh NAME
@@ -53,12 +53,34 @@
 .Op Fl s Ar avgfpdir
 .Op Fl S Ar size
 .Op Fl t Cm enable | disable
-.Ar special | filesystem
+.Ar filesystem
 .Sh DESCRIPTION
 The
 .Nm
 utility is designed to change the dynamic parameters of a UFS file system
 which affect the layout policies.
+.Pp
+The file system to be operated on is a block device special name,
+a file system path, or a UFS file system image as a regular file
+.Pq Ar filesystem .
+.Pp
+.Nm
+searches for a valid filesystem in several places.
+First it will examine
+.Ar filesystem
+as a file, a file system path, or a device name under
+.Pa /dev .
+If none of these match,
+.Nm
+will read
+.Pa /etc/fstab
+and try to match
+.Ar filesystem
+to a device special name or a file system.
+If the file system to be tuned has been mounted by hand,
+.Nm
+will also look for the file system as a directory.
+.Pp
 The
 .Nm
 utility cannot be run on an active file system.