diff --git a/bin/ps/extern.h b/bin/ps/extern.h
index a322d568b3ae..7c684601b669 100644
--- a/bin/ps/extern.h
+++ b/bin/ps/extern.h
@@ -77,5 +77,6 @@ void	 uname(KINFO *, VARENT *);
 int	 s_uname(KINFO *);
 void	 vsize(KINFO *, VARENT *);
 void	 wchan(KINFO *, VARENT *);
+void	 mwchan(KINFO *, VARENT *);
 void	 lattr(KINFO *, VARENT *);
 __END_DECLS
diff --git a/bin/ps/keyword.c b/bin/ps/keyword.c
index b5cc1524ef4c..e1ff7ba86070 100644
--- a/bin/ps/keyword.c
+++ b/bin/ps/keyword.c
@@ -119,6 +119,7 @@ static VAR var[] = {
 		LONG, "ld", 0},
 	{"mtxname", "MUTEX", NULL, LJUST, mtxname, NULL, 6, 0, CHAR, NULL,
 		0},
+	{"mwchan", "MWCHAN", NULL, LJUST, mwchan, NULL, 6, 0, CHAR, NULL, 0},
 	{"ni", "", "nice", 0, NULL, NULL, 0, 0, CHAR, NULL, 0},
 	{"nice", "NI", NULL, 0, kvar, NULL, 2, KOFF(ki_nice), CHAR, "d",
 		0},
diff --git a/bin/ps/print.c b/bin/ps/print.c
index 4de0dd792e68..74e7f8fc686a 100644
--- a/bin/ps/print.c
+++ b/bin/ps/print.c
@@ -401,6 +401,24 @@ wchan(KINFO *k, VARENT *ve)
 {
 	VAR *v;
 
+	v = ve->var;
+	if (k->ki_p->ki_wchan) {
+		if (k->ki_p->ki_wmesg[0] != 0)
+			(void)printf("%-*.*s", v->width, v->width,
+				      k->ki_p->ki_wmesg);
+		else
+			(void)printf("%-*lx", v->width,
+			    (long)k->ki_p->ki_wchan);
+	} else {
+		(void)printf("%-*s", v->width, "-");
+	}
+}
+
+void
+mwchan(KINFO *k, VARENT *ve)
+{
+	VAR *v;
+
 	v = ve->var;
 	if (k->ki_p->ki_wchan) {
 		if (k->ki_p->ki_wmesg[0] != 0)
@@ -410,7 +428,12 @@ wchan(KINFO *k, VARENT *ve)
 			(void)printf("%-*lx", v->width,
 			    (long)k->ki_p->ki_wchan);
 	} else if (k->ki_p->ki_kiflag & KI_MTXBLOCK) {
-		(void)printf("%-*.*s", v->width, v->width, k->ki_p->ki_mtxname);
+		if (k->ki_p->ki_mtxname[0]) {
+			(void)printf("%-*.*s", v->width, v->width,
+			    k->ki_p->ki_mtxname);
+		} else {
+			(void)printf("%-*s", v->width, "???");
+		}
 	} else {
 		(void)printf("%-*s", v->width, "-");
 	}
diff --git a/bin/ps/ps.1 b/bin/ps/ps.1
index b9237e824558..32402e710f90 100644
--- a/bin/ps/ps.1
+++ b/bin/ps/ps.1
@@ -106,7 +106,7 @@ user, pid, ppid, pgid, jobc, state, tt, time and command.
 List the set of available keywords.
 .It Fl l
 Display information associated with the following keywords:
-uid, pid, ppid, cpu, pri, nice, vsz, rss, wchan, state, tt, time
+uid, pid, ppid, cpu, pri, nice, vsz, rss, mwchan, state, tt, time
 and command.
 .It Fl M
 Extract values associated with the name list from the specified core
@@ -234,6 +234,10 @@ that the process is currently blocked on.
 If the name is invalid or unknown, then
 .Dq ???\&
 is displayed.
+.It mwchan
+The event name if the process is blocked normally, or the mutex name if
+the process is blocked on a mutex.  See the wchan and mtxname keywords
+for details.
 .It nice
 The process scheduling increment (see
 .Xr setpriority 2 ) .
@@ -393,6 +397,8 @@ total messages sent (writes on pipes/sockets)
 .It mtxname
 .Xr mutex 9
 currently blocked on (as a symbolic name)
+.It mwchan
+wait channel or mutex currently blocked on
 .It nice
 nice value (alias ni)
 .It nivcsw
diff --git a/bin/ps/ps.c b/bin/ps/ps.c
index 0897ccbced1e..55445e72da8c 100644
--- a/bin/ps/ps.c
+++ b/bin/ps/ps.c
@@ -103,7 +103,7 @@ static uid_t	*getuids(const char *, int *);
 
 static char dfmt[] = "pid tt state time command";
 static char jfmt[] = "user pid ppid pgid jobc state tt time command";
-static char lfmt[] = "uid pid ppid cpu pri nice vsz rss wchan state tt time command";
+static char lfmt[] = "uid pid ppid cpu pri nice vsz rss mwchan state tt time command";
 static char   o1[] = "pid";
 static char   o2[] = "tt state time command";
 static char ufmt[] = "user pid %cpu %mem vsz rss tt state start time command";