diff --git a/client.c b/client.c
index 7d997a7e..9c493dfa 100644
--- a/client.c
+++ b/client.c
@@ -352,9 +352,10 @@ client_main(int argc, char **argv, int flags)
 void
 client_send_identify(int flags)
 {
-	const char	*s;
+	const char	 *s;
 	char		**ss;
-	int		 fd;
+	int		  fd;
+	pid_t		  pid;
 
 	client_write_one(MSG_IDENTIFY_FLAGS, -1, &flags, sizeof flags);
 
@@ -374,6 +375,9 @@ client_send_identify(int flags)
 		fatal("dup failed");
 	client_write_one(MSG_IDENTIFY_STDIN, fd, NULL, 0);
 
+	pid = getpid();
+	client_write_one(MSG_IDENTIFY_CLIENTPID, -1, &pid, sizeof pid);
+
 	for (ss = environ; *ss != NULL; ss++)
 		client_write_one(MSG_IDENTIFY_ENVIRON, -1, *ss, strlen(*ss) + 1);
 
diff --git a/format.c b/format.c
index d323d32f..f562f23e 100644
--- a/format.c
+++ b/format.c
@@ -272,6 +272,7 @@ format_create_status(int status)
 			*ptr = '\0';
 		format_add(ft, "host_short", "%s", host);
 	}
+	format_add(ft, "pid", "%ld", (long) getpid());
 
 	return (ft);
 }
@@ -704,6 +705,7 @@ format_defaults_client(struct format_tree *ft, struct client *c)
 	if (ft->s == NULL)
 		ft->s = c->session;
 
+	format_add(ft, "client_pid", "%ld", (long) c->pid);
 	format_add(ft, "client_height", "%u", c->tty.sy);
 	format_add(ft, "client_width", "%u", c->tty.sx);
 	if (c->tty.path != NULL)
diff --git a/server-client.c b/server-client.c
index 27efc57d..c9c0c3ef 100644
--- a/server-client.c
+++ b/server-client.c
@@ -1053,6 +1053,7 @@ server_client_msg_dispatch(struct client *c)
 		case MSG_IDENTIFY_CWD:
 		case MSG_IDENTIFY_STDIN:
 		case MSG_IDENTIFY_ENVIRON:
+		case MSG_IDENTIFY_CLIENTPID:
 		case MSG_IDENTIFY_DONE:
 			server_client_msg_identify(c, &imsg);
 			break;
@@ -1227,6 +1228,11 @@ server_client_msg_identify(struct client *c, struct imsg *imsg)
 		if (strchr(data, '=') != NULL)
 			environ_put(&c->environ, data);
 		break;
+	case MSG_IDENTIFY_CLIENTPID:
+		if (datalen != sizeof c->pid)
+			fatalx("bad MSG_IDENTIFY_CLIENTPID size");
+		memcpy(&c->pid, data, sizeof c->pid);
+		break;
 	default:
 		break;
 	}
diff --git a/tmux.1 b/tmux.1
index f3eeabcc..8fed79e7 100644
--- a/tmux.1
+++ b/tmux.1
@@ -3357,6 +3357,7 @@ The following variables are available, where appropriate:
 .It Li "client_created_string" Ta "" Ta "String time client created"
 .It Li "client_height" Ta "" Ta "Height of client"
 .It Li "client_last_session" Ta "" Ta "Name of the client's last session"
+.It Li "client_pid" Ta "" Ta "PID of client process"
 .It Li "client_prefix" Ta "" Ta "1 if prefix key has been pressed"
 .It Li "client_readonly" Ta "" Ta "1 if client is readonly"
 .It Li "client_session" Ta "" Ta "Name of the client's session"
@@ -3401,6 +3402,7 @@ The following variables are available, where appropriate:
 .It Li "pane_top" Ta "" Ta "Top of pane"
 .It Li "pane_tty" Ta "" Ta "Pseudo terminal of pane"
 .It Li "pane_width" Ta "" Ta "Width of pane"
+.It Li "pid" Ta ""  Ta "Server PID"
 .It Li "scroll_region_lower" Ta "" Ta "Bottom of scroll region in pane"
 .It Li "scroll_region_upper" Ta "" Ta "Top of scroll region in pane"
 .It Li "session_alerts" Ta "" Ta "List of window indexes with alerts"
diff --git a/tmux.h b/tmux.h
index 210826ad..7ba1b0b2 100644
--- a/tmux.h
+++ b/tmux.h
@@ -429,6 +429,7 @@ enum msgtype {
 	MSG_IDENTIFY_STDIN,
 	MSG_IDENTIFY_ENVIRON,
 	MSG_IDENTIFY_DONE,
+	MSG_IDENTIFY_CLIENTPID,
 
 	MSG_COMMAND = 200,
 	MSG_DETACH,
@@ -1210,6 +1211,7 @@ RB_HEAD(status_out_tree, status_out);
 struct client {
 	struct imsgbuf	 ibuf;
 
+	pid_t		 pid;
 	int		 fd;
 	struct event	 event;
 	int		 retval;