diff --git a/Makefile.am b/Makefile.am
index e8b35802..fe520a01 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -178,6 +178,7 @@ dist_tmate_SOURCES = \
 	tmate-ssh-client.c \
 	tmate-encoder.c \
 	tmate-decoder.c \
+	tmate-env.c \
 	tmate-msg.c \
 	tmate-session.c \
 	tmux.c \
diff --git a/cmd-wait-for.c b/cmd-wait-for.c
index d40ba49e..ea36255d 100644
--- a/cmd-wait-for.c
+++ b/cmd-wait-for.c
@@ -23,6 +23,7 @@
 #include <string.h>
 
 #include "tmux.h"
+#include "tmate.h"
 
 /*
  * Block or wake a client on a named wait channel.
@@ -116,10 +117,44 @@ cmd_wait_for_signal(struct cmd_q *cmdq, const char *name,
 	return (CMD_RETURN_NORMAL);
 }
 
+#ifdef TMATE
+void signal_waiting_clients(const char *name)
+{
+	struct wait_channel	*wc, wc0;
+	struct cmd_q	*wq, *wq1;
+
+	wc0.name = name;
+	wc = RB_FIND(wait_channels, &wait_channels, &wc0);
+
+	if (wc == NULL || TAILQ_EMPTY(&wc->waiters)) {
+		return;
+	}
+
+	TAILQ_FOREACH_SAFE(wq, &wc->waiters, waitentry, wq1) {
+		TAILQ_REMOVE(&wc->waiters, wq, waitentry);
+		if (!cmdq_free(wq))
+			cmdq_continue(wq);
+	}
+
+	if (!wc->locked) {
+		RB_REMOVE(wait_channels, &wait_channels, wc);
+		free((void*) wc->name);
+		free(wc);
+	}
+}
+#endif
+
 enum cmd_retval
 cmd_wait_for_wait(struct cmd_q *cmdq, const char *name,
     struct wait_channel *wc)
 {
+
+#ifdef TMATE
+	if (!strcmp(name, "tmate-ready") && tmate_session.decoder.ready)
+		return (CMD_RETURN_NORMAL);
+#endif
+
+
 	if (cmdq->client == NULL || cmdq->client->session != NULL) {
 		cmdq_error(cmdq, "not able to wait");
 		return (CMD_RETURN_ERROR);
diff --git a/format.c b/format.c
index fa2dd0b2..4acae393 100644
--- a/format.c
+++ b/format.c
@@ -26,6 +26,7 @@
 #include <unistd.h>
 
 #include "tmux.h"
+#include "tmate.h"
 
 /*
  * Build a list of key-value pairs and use them to expand #{key} entries in a
@@ -214,6 +215,10 @@ format_expand(struct format_tree *ft, const char *fmt)
 	size_t		 off, len, n;
 	int     	 ch;
 
+#ifdef TMATE
+	tmate_format(ft);
+#endif
+
 	len = 64;
 	buf = xmalloc(len);
 	off = 0;
diff --git a/tmate-decoder.c b/tmate-decoder.c
index 3e780dc5..7489d76f 100644
--- a/tmate-decoder.c
+++ b/tmate-decoder.c
@@ -148,7 +148,27 @@ out:
 	free(cmd_str);
 }
 
-static void handle_message(msgpack_object obj)
+static void tmate_client_env(struct tmate_unpacker *uk)
+{
+	char *name = unpack_string(uk);
+	char *value = unpack_string(uk);
+
+	tmate_set_env(name, value);
+
+	free(name);
+	free(value);
+}
+
+
+extern void signal_waiting_clients(const char *name);
+static void tmate_client_ready(struct tmate_decoder *decoder,
+			       struct tmate_unpacker *uk)
+{
+	decoder->ready = 1;
+	signal_waiting_clients("tmate-ready");
+}
+
+static void handle_message(struct tmate_decoder *decoder, msgpack_object obj)
 {
 	struct tmate_unpacker _uk;
 	struct tmate_unpacker *uk = &_uk;
@@ -160,6 +180,8 @@ static void handle_message(msgpack_object obj)
 	case TMATE_CLIENT_PANE_KEY:	tmate_client_pane_key(uk); break;
 	case TMATE_CLIENT_RESIZE:	tmate_client_resize(uk); break;
 	case TMATE_CLIENT_EXEC_CMD:	tmate_client_exec_cmd(uk); break;
+	case TMATE_CLIENT_ENV:		tmate_client_env(uk); break;
+	case TMATE_CLIENT_READY:	tmate_client_ready(decoder, uk); break;
 	default:			decoder_error();
 	}
 }
@@ -172,7 +194,7 @@ void tmate_decoder_commit(struct tmate_decoder *decoder, size_t len)
 
 	msgpack_unpacked_init(&result);
 	while (msgpack_unpacker_next(&decoder->unpacker, &result)) {
-		handle_message(result.data);
+		handle_message(decoder, result.data);
 	}
 	msgpack_unpacked_destroy(&result);
 
@@ -199,4 +221,5 @@ void tmate_decoder_init(struct tmate_decoder *decoder)
 {
 	if (!msgpack_unpacker_init(&decoder->unpacker, 2*TMATE_MAX_MESSAGE_SIZE))
 		tmate_fatal("cannot initialize the unpacker");
+	decoder->ready = 0;
 }
diff --git a/tmate-env.c b/tmate-env.c
new file mode 100644
index 00000000..92abf069
--- /dev/null
+++ b/tmate-env.c
@@ -0,0 +1,36 @@
+#include "tmate.h"
+
+struct tmate_env {
+	TAILQ_ENTRY(tmate_env) entry;
+	char *name;
+	char *value;
+};
+
+TAILQ_HEAD(, tmate_env) tmate_env_list;
+
+void tmate_set_env(const char *name, const char *value)
+{
+	struct tmate_env *tmate_env;
+
+	TAILQ_FOREACH(tmate_env, &tmate_env_list, entry) {
+		if (!strcmp(tmate_env->name, name)) {
+			free(tmate_env->value);
+			tmate_env->value = xstrdup(value);
+			return;
+		}
+	}
+
+	tmate_env = xmalloc(sizeof(*tmate_env));
+	tmate_env->name = xstrdup(name);
+	tmate_env->value = xstrdup(value);
+	TAILQ_INSERT_HEAD(&tmate_env_list, tmate_env, entry);
+}
+
+void tmate_format(struct format_tree *ft)
+{
+	struct tmate_env *tmate_env;
+
+	TAILQ_FOREACH(tmate_env, &tmate_env_list, entry) {
+		format_add(ft, tmate_env->name, "%s", tmate_env->value);
+	}
+}
diff --git a/tmate.h b/tmate.h
index ab202cf7..344015d1 100644
--- a/tmate.h
+++ b/tmate.h
@@ -18,7 +18,7 @@
 
 #define TMATE_MAX_MESSAGE_SIZE (16*1024)
 
-#define TMATE_PROTOCOL_VERSION 3
+#define TMATE_PROTOCOL_VERSION 4
 
 enum tmate_commands {
 	TMATE_HEADER,
@@ -56,10 +56,13 @@ enum tmate_client_commands {
 	TMATE_CLIENT_PANE_KEY,
 	TMATE_CLIENT_RESIZE,
 	TMATE_CLIENT_EXEC_CMD,
+	TMATE_CLIENT_ENV,
+	TMATE_CLIENT_READY,
 };
 
 struct tmate_decoder {
 	struct msgpack_unpacker unpacker;
+	int ready;
 };
 
 extern int tmate_sx;
@@ -147,4 +150,10 @@ extern void tmate_catch_sigsegv(void);
 extern void __tmate_status_message(const char *fmt, va_list ap);
 extern void printflike1 tmate_status_message(const char *fmt, ...);
 
+/* tmate-env.c */
+
+extern int tmate_has_received_env(void);
+extern void tmate_set_env(const char *name, const char *value);
+extern void tmate_format(struct format_tree *ft);
+
 #endif