diff --git a/sbin/tunefs/tunefs.8 b/sbin/tunefs/tunefs.8
--- a/sbin/tunefs/tunefs.8
+++ b/sbin/tunefs/tunefs.8
@@ -25,7 +25,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd November 17, 2023
+.Dd February 6, 2025
 .Dt TUNEFS 8
 .Os
 .Sh NAME
@@ -50,12 +50,34 @@
 .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 those 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.
diff --git a/sbin/tunefs/tunefs.c b/sbin/tunefs/tunefs.c
--- a/sbin/tunefs/tunefs.c
+++ b/sbin/tunefs/tunefs.c
@@ -1060,7 +1060,7 @@
 "              [-L volname] [-l enable | disable] [-m minfree]",
 "              [-N enable | disable] [-n enable | disable]",
 "              [-o space | time] [-p] [-s avgfpdir] [-t enable | disable]",
-"              special | filesystem");
+"              filesystem");
 	exit(2);
 }