diff --git a/sbin/dmesg/dmesg.8 b/sbin/dmesg/dmesg.8
index 45b605f3ea81..a7fa95e7b3d4 100644
--- a/sbin/dmesg/dmesg.8
+++ b/sbin/dmesg/dmesg.8
@@ -41,22 +41,19 @@
 .Sh SYNOPSIS
 .Nm
 .Op Fl a
-.Op Fl M Ar core
-.Op Fl N Ar system
+.Op Fl M Ar core Op Fl N Ar system
 .Sh DESCRIPTION
 The
 .Nm
 utility displays the contents of the system message buffer.
-If neither the
-.Fl N
-nor the
+If the
 .Fl M
-option is specified, the buffer is read from the currently running kernel
+option is not specified, the buffer is read from the currently running kernel
 via the
 .Xr sysctl 3
 interface.
-Otherwise, the buffer is read from the specified core file (or from the
-default one), using the name list from the specified kernel image (or from
+Otherwise, the buffer is read from the specified core file,
+using the name list from the specified kernel image (or from
 the default image).
 .Pp
 The options are as follows:
@@ -67,11 +64,12 @@ This includes any syslog records and
 .Pa /dev/console
 output.
 .It Fl M
-Extract values associated with the name list from the specified core
-instead of the default
-.Pa /dev/kmem .
+Extract values associated with the name list from the specified core.
 .It Fl N
-Extract the name list from the specified system instead of the default,
+If
+.Fl M
+is also specified,
+extract the name list from the specified system instead of the default,
 which is the kernel image the system has booted from.
 .El
 .Sh FILES
diff --git a/sbin/dmesg/dmesg.c b/sbin/dmesg/dmesg.c
index 57f543bb6229..08cc732127cc 100644
--- a/sbin/dmesg/dmesg.c
+++ b/sbin/dmesg/dmesg.c
@@ -105,7 +105,7 @@ main(int argc, char *argv[])
 	argc -= optind;
 	argv += optind;
 
-	if (memf == NULL && nlistf == NULL) {
+	if (memf == NULL) {
 		/*
 		 * Running kernel.  Use sysctl.  This gives an unwrapped
 		 * buffer as a side effect.
@@ -196,6 +196,6 @@ main(int argc, char *argv[])
 void
 usage(void)
 {
-	(void)fprintf(stderr, "usage: dmesg [-a] [-M core] [-N system]\n");
+	(void)fprintf(stderr, "usage: dmesg [-a] [-M core [-N system]]\n");
 	exit(1);
 }