diff --git a/usr.sbin/diskinfo/diskinfo.8 b/usr.sbin/diskinfo/diskinfo.8
index 17562644a4c5..a89c25da03f8 100644
--- a/usr.sbin/diskinfo/diskinfo.8
+++ b/usr.sbin/diskinfo/diskinfo.8
@@ -36,8 +36,7 @@
 .Nd get information about disk device
 .Sh SYNOPSIS
 .Nm
-.Op Fl v
-.Op Fl t
+.Op Fl tv
 .Ar disk ...
 .Sh DESCRIPTION
 The
diff --git a/usr.sbin/diskinfo/diskinfo.c b/usr.sbin/diskinfo/diskinfo.c
index 45837f626399..5025e510f96d 100644
--- a/usr.sbin/diskinfo/diskinfo.c
+++ b/usr.sbin/diskinfo/diskinfo.c
@@ -41,7 +41,7 @@
 static void
 usage(void)
 {
-	fprintf(stderr, "Usage: diskinfo [-tv]\n");
+	fprintf(stderr, "usage: diskinfo [-tv] disk ...\n");
 	exit (1);
 }
 
@@ -73,6 +73,9 @@ main(int argc, char **argv)
 	argc -= optind;
 	argv += optind;
 
+	if (argc < 1)
+		usage();
+
 	for (i = 0; i < argc; i++) {
 		fd = open(argv[i], O_RDONLY);
 		if (fd < 0 && errno == ENOENT && *argv[i] != '/') {