diff --git a/client.c b/client.c
index 852b09ce..f08d6f29 100644
--- a/client.c
+++ b/client.c
@@ -59,7 +59,8 @@ static struct client_files client_files = RB_INITIALIZER(&client_files);
 
 static __dead void	 client_exec(const char *,const char *);
 static int		 client_get_lock(char *);
-static int		 client_connect(struct event_base *, const char *, int);
+static int		 client_connect(struct event_base *, const char *,
+			     uint64_t);
 static void		 client_send_identify(const char *, const char *, int);
 static void		 client_signal(int);
 static void		 client_dispatch(struct imsg *, void *);
@@ -100,7 +101,7 @@ client_get_lock(char *lockfile)
 
 /* Connect client to server. */
 static int
-client_connect(struct event_base *base, const char *path, int flags)
+client_connect(struct event_base *base, const char *path, uint64_t flags)
 {
 	struct sockaddr_un	sa;
 	size_t			size;
@@ -238,7 +239,8 @@ client_exit(void)
 
 /* Client main loop. */
 int
-client_main(struct event_base *base, int argc, char **argv, int flags, int feat)
+client_main(struct event_base *base, int argc, char **argv, uint64_t flags,
+    int feat)
 {
 	struct cmd_parse_result	*pr;
 	struct msg_command	*data;
@@ -284,7 +286,7 @@ client_main(struct event_base *base, int argc, char **argv, int flags, int feat)
 
 	/* Save the flags. */
 	client_flags = flags;
-	log_debug("flags are %#llx", client_flags);
+	log_debug("flags are %#llx", (unsigned long long)client_flags);
 
 	/* Initialize the client socket and start the server. */
 	fd = client_connect(base, socket_path, client_flags);
@@ -440,6 +442,8 @@ client_send_identify(const char *ttynam, const char *cwd, int feat)
 	pid_t		  pid;
 
 	proc_send(client_peer, MSG_IDENTIFY_FLAGS, -1, &flags, sizeof flags);
+	proc_send(client_peer, MSG_IDENTIFY_LONGFLAGS, -1, &client_flags,
+	    sizeof client_flags);
 
 	if ((s = getenv("TERM")) == NULL)
 		s = "";
@@ -889,7 +893,8 @@ client_dispatch_wait(struct imsg *imsg)
 			fatalx("bad MSG_FLAGS string");
 
 		memcpy(&client_flags, data, sizeof client_flags);
-		log_debug("new flags are %#llx", client_flags);
+		log_debug("new flags are %#llx",
+		    (unsigned long long)client_flags);
 		break;
 	case MSG_SHELL:
 		if (datalen == 0 || data[datalen - 1] != '\0')
@@ -942,7 +947,8 @@ client_dispatch_attached(struct imsg *imsg)
 			fatalx("bad MSG_FLAGS string");
 
 		memcpy(&client_flags, data, sizeof client_flags);
-		log_debug("new flags are %#llx", client_flags);
+		log_debug("new flags are %#llx",
+		    (unsigned long long)client_flags);
 		break;
 	case MSG_DETACH:
 	case MSG_DETACHKILL:
diff --git a/server-client.c b/server-client.c
index 4010019d..efeec85b 100644
--- a/server-client.c
+++ b/server-client.c
@@ -1985,6 +1985,7 @@ server_client_dispatch(struct imsg *imsg, void *arg)
 	switch (imsg->hdr.type) {
 	case MSG_IDENTIFY_FEATURES:
 	case MSG_IDENTIFY_FLAGS:
+	case MSG_IDENTIFY_LONGFLAGS:
 	case MSG_IDENTIFY_TERM:
 	case MSG_IDENTIFY_TTYNAME:
 	case MSG_IDENTIFY_CWD:
@@ -2143,6 +2144,7 @@ server_client_dispatch_identify(struct client *c, struct imsg *imsg)
 	const char	*data, *home;
 	size_t		 datalen;
 	int		 flags, feat;
+	uint64_t	 longflags;
 	char		*name;
 
 	if (c->flags & CLIENT_IDENTIFIED)
@@ -2167,6 +2169,14 @@ server_client_dispatch_identify(struct client *c, struct imsg *imsg)
 		c->flags |= flags;
 		log_debug("client %p IDENTIFY_FLAGS %#x", c, flags);
 		break;
+	case MSG_IDENTIFY_LONGFLAGS:
+		if (datalen != sizeof longflags)
+			fatalx("bad MSG_IDENTIFY_LONGFLAGS size");
+		memcpy(&longflags, data, sizeof longflags);
+		c->flags |= longflags;
+		log_debug("client %p IDENTIFY_LONGFLAGS %#llx", c,
+		    (unsigned long long)longflags);
+		break;
 	case MSG_IDENTIFY_TERM:
 		if (datalen == 0 || data[datalen - 1] != '\0')
 			fatalx("bad MSG_IDENTIFY_TERM string");
diff --git a/tmux.c b/tmux.c
index a9aec43d..b7fc5121 100644
--- a/tmux.c
+++ b/tmux.c
@@ -331,8 +331,8 @@ main(int argc, char **argv)
 	char					*path = NULL, *label = NULL;
 	char					*cause, **var;
 	const char				*s, *shell, *cwd;
-	int					 opt, flags = 0, keys;
-	int					 feat = 0;
+	int					 opt, keys, feat = 0;
+	uint64_t				 flags = 0;
 	const struct options_table_entry	*oe;
 
 	if (setlocale(LC_CTYPE, "en_US.UTF-8") == NULL &&
diff --git a/tmux.h b/tmux.h
index 9fb3830a..dd8ac2c1 100644
--- a/tmux.h
+++ b/tmux.h
@@ -496,6 +496,7 @@ enum msgtype {
 	MSG_IDENTIFY_CWD,
 	MSG_IDENTIFY_FEATURES,
 	MSG_IDENTIFY_STDOUT,
+	MSG_IDENTIFY_LONGFLAGS,
 
 	MSG_COMMAND = 200,
 	MSG_DETACH,
@@ -2331,7 +2332,7 @@ void printflike(2, 3) cmdq_error(struct cmdq_item *, const char *, ...);
 void	cmd_wait_for_flush(void);
 
 /* client.c */
-int	client_main(struct event_base *, int, char **, int, int);
+int	client_main(struct event_base *, int, char **, uint64_t, int);
 
 /* key-bindings.c */
 struct key_table *key_bindings_get_table(const char *, int);