diff --git a/ssh.c b/ssh.c
index fb24f435..87fabfbd 100644
--- a/ssh.c
+++ b/ssh.c
@@ -560,10 +560,12 @@ struct ssh_channel {
      * A channel is completely finished with when all four bits are set.
      */
     int closes;
+    /*
+     * True if this channel is causing the underlying connection to be
+     * throttled.
+     */
+    int throttling_conn;
     union {
-	struct ssh1_data_channel {
-	    int throttling;
-	} v1;
 	struct ssh2_data_channel {
 	    bufchain outbuffer;
 	    unsigned remwindow, remmaxpkt;
@@ -810,7 +812,7 @@ struct ssh_tag {
     void *x11auth;
 
     int version;
-    int v1_throttle_count;
+    int conn_throttle_count;
     int overall_bufsize;
     int throttled_all;
     int v1_stdout_throttling;
@@ -2873,14 +2875,14 @@ static const char *connect_to_host(Ssh ssh, char *host, int port,
 /*
  * Throttle or unthrottle the SSH connection.
  */
-static void ssh1_throttle(Ssh ssh, int adjust)
+static void ssh_throttle_conn(Ssh ssh, int adjust)
 {
-    int old_count = ssh->v1_throttle_count;
-    ssh->v1_throttle_count += adjust;
-    assert(ssh->v1_throttle_count >= 0);
-    if (ssh->v1_throttle_count && !old_count) {
+    int old_count = ssh->conn_throttle_count;
+    ssh->conn_throttle_count += adjust;
+    assert(ssh->conn_throttle_count >= 0);
+    if (ssh->conn_throttle_count && !old_count) {
 	ssh_set_frozen(ssh, 1);
-    } else if (!ssh->v1_throttle_count && old_count) {
+    } else if (!ssh->conn_throttle_count && old_count) {
 	ssh_set_frozen(ssh, 0);
     }
 }
@@ -4054,17 +4056,20 @@ int sshfwd_write(struct ssh_channel *c, char *buf, int len)
 void sshfwd_unthrottle(struct ssh_channel *c, int bufsize)
 {
     Ssh ssh = c->ssh;
+    int buflimit;
 
     if (ssh->state == SSH_STATE_CLOSED)
 	return;
 
     if (ssh->version == 1) {
-	if (c->v.v1.throttling && bufsize < SSH1_BUFFER_LIMIT) {
-	    c->v.v1.throttling = 0;
-	    ssh1_throttle(ssh, -1);
-	}
+	buflimit = SSH1_BUFFER_LIMIT;
     } else {
-	ssh2_set_window(c, c->v.v2.locmaxwin - bufsize);
+	buflimit = c->v.v2.locmaxwin;
+	ssh2_set_window(c, bufsize < buflimit ? buflimit - bufsize : 0);
+    }
+    if (c->throttling_conn && bufsize <= buflimit) {
+	c->throttling_conn = 0;
+	ssh_throttle_conn(ssh, -1);
     }
 }
 
@@ -4493,7 +4498,7 @@ static void ssh1_smsg_stdout_stderr_data(Ssh ssh, struct Packet *pktin)
 			   string, stringlen);
     if (!ssh->v1_stdout_throttling && bufsize > SSH1_BUFFER_LIMIT) {
 	ssh->v1_stdout_throttling = 1;
-	ssh1_throttle(ssh, +1);
+	ssh_throttle_conn(ssh, +1);
     }
 }
 
@@ -4527,7 +4532,7 @@ static void ssh1_smsg_x11_open(Ssh ssh, struct Packet *pktin)
 	    c->halfopen = FALSE;
 	    c->localid = alloc_channel_id(ssh);
 	    c->closes = 0;
-	    c->v.v1.throttling = 0;
+	    c->throttling_conn = 0;
 	    c->type = CHAN_X11;	/* identify channel type */
 	    add234(ssh->channels, c);
 	    send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
@@ -4556,7 +4561,7 @@ static void ssh1_smsg_agent_open(Ssh ssh, struct Packet *pktin)
 	c->halfopen = FALSE;
 	c->localid = alloc_channel_id(ssh);
 	c->closes = 0;
-	c->v.v1.throttling = 0;
+	c->throttling_conn = 0;
 	c->type = CHAN_AGENT;	/* identify channel type */
 	c->u.a.lensofar = 0;
 	add234(ssh->channels, c);
@@ -4610,7 +4615,7 @@ static void ssh1_msg_port_open(Ssh ssh, struct Packet *pktin)
 	    c->halfopen = FALSE;
 	    c->localid = alloc_channel_id(ssh);
 	    c->closes = 0;
-	    c->v.v1.throttling = 0;
+	    c->throttling_conn = 0;
 	    c->type = CHAN_SOCKDATA;	/* identify channel type */
 	    add234(ssh->channels, c);
 	    send_packet(ssh, SSH1_MSG_CHANNEL_OPEN_CONFIRMATION,
@@ -4632,7 +4637,7 @@ static void ssh1_msg_channel_open_confirmation(Ssh ssh, struct Packet *pktin)
 	c->remoteid = localid;
 	c->halfopen = FALSE;
 	c->type = CHAN_SOCKDATA;
-	c->v.v1.throttling = 0;
+	c->throttling_conn = 0;
 	pfd_confirm(c->u.pfd.s);
     }
 
@@ -4768,9 +4773,9 @@ static void ssh1_msg_channel_data(Ssh ssh, struct Packet *pktin)
 	    bufsize = 0;   /* agent channels never back up */
 	    break;
 	}
-	if (!c->v.v1.throttling && bufsize > SSH1_BUFFER_LIMIT) {
-	    c->v.v1.throttling = 1;
-	    ssh1_throttle(ssh, +1);
+	if (!c->throttling_conn && bufsize > SSH1_BUFFER_LIMIT) {
+	    c->throttling_conn = 1;
+	    ssh_throttle_conn(ssh, +1);
 	}
     }
 }
@@ -6458,6 +6463,17 @@ static void ssh2_msg_channel_data(Ssh ssh, struct Packet *pktin)
 	 */
 	ssh2_set_window(c, bufsize < c->v.v2.locmaxwin ?
 			c->v.v2.locmaxwin - bufsize : 0);
+	/*
+	 * If we're either buffering way too much data, or if we're
+	 * buffering anything at all and we're in "simple" mode,
+	 * throttle the whole channel.
+	 */
+	if ((bufsize > c->v.v2.locmaxwin ||
+	     (ssh->cfg.ssh_simple && bufsize > 0)) &&
+	    !c->throttling_conn) {
+	    c->throttling_conn = 1;
+	    ssh_throttle_conn(ssh, +1);
+	}
     }
 }
 
@@ -6905,6 +6921,7 @@ static void ssh2_msg_channel_open(Ssh ssh, struct Packet *pktin)
     } else {
 	c->localid = alloc_channel_id(ssh);
 	c->closes = 0;
+	c->throttling_conn = FALSE;
 	c->v.v2.locwindow = c->v.v2.locmaxwin = OUR_V2_WINSIZE;
 	c->v.v2.remwindow = winsize;
 	c->v.v2.remmaxpkt = pktsize;
@@ -8119,6 +8136,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 	s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN);
 	ssh2_pkt_addstring(s->pktout, "direct-tcpip");
 	ssh2_pkt_adduint32(s->pktout, ssh->mainchan->localid);
+	ssh->mainchan->throttling_conn = FALSE;
 	ssh->mainchan->v.v2.locwindow = ssh->mainchan->v.v2.locmaxwin =
 	    ssh->mainchan->v.v2.remlocwin =
 	    ssh->cfg.ssh_simple ? OUR_V2_BIGWIN : OUR_V2_WINSIZE;
@@ -8166,6 +8184,7 @@ static void do_ssh2_authconn(Ssh ssh, unsigned char *in, int inlen,
 	s->pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN);
 	ssh2_pkt_addstring(s->pktout, "session");
 	ssh2_pkt_adduint32(s->pktout, ssh->mainchan->localid);
+	ssh->mainchan->throttling_conn = FALSE;
 	ssh->mainchan->v.v2.locwindow = ssh->mainchan->v.v2.locmaxwin =
 	    ssh->mainchan->v.v2.remlocwin =
 	    ssh->cfg.ssh_simple ? OUR_V2_BIGWIN : OUR_V2_WINSIZE;
@@ -8792,7 +8811,7 @@ static const char *ssh_init(void *frontend_handle, void **backend_handle,
     ssh->send_ok = 0;
     ssh->editing = 0;
     ssh->echoing = 0;
-    ssh->v1_throttle_count = 0;
+    ssh->conn_throttle_count = 0;
     ssh->overall_bufsize = 0;
     ssh->fallback_cmd = 0;
 
@@ -9239,15 +9258,27 @@ void *new_sock_channel(void *handle, Socket s)
 static void ssh_unthrottle(void *handle, int bufsize)
 {
     Ssh ssh = (Ssh) handle;
+    int buflimit;
+
     if (ssh->version == 1) {
 	if (ssh->v1_stdout_throttling && bufsize < SSH1_BUFFER_LIMIT) {
 	    ssh->v1_stdout_throttling = 0;
-	    ssh1_throttle(ssh, -1);
+	    ssh_throttle_conn(ssh, -1);
 	}
     } else {
-	if (ssh->mainchan)
+	if (ssh->mainchan) {
 	    ssh2_set_window(ssh->mainchan,
-			    ssh->mainchan->v.v2.locmaxwin - bufsize);
+			    bufsize < ssh->mainchan->v.v2.locmaxwin ?
+			    ssh->mainchan->v.v2.locmaxwin - bufsize : 0);
+	    if (ssh->cfg.ssh_simple)
+		buflimit = 0;
+	    else
+		buflimit = ssh->mainchan->v.v2.locmaxwin;
+	    if (ssh->mainchan->throttling_conn && bufsize <= buflimit) {
+		ssh->mainchan->throttling_conn = 0;
+		ssh_throttle_conn(ssh, -1);
+	    }
+	}
     }
 }
 
@@ -9270,6 +9301,7 @@ void ssh_send_port_open(void *channel, char *hostname, int port, char *org)
 	pktout = ssh2_pkt_init(SSH2_MSG_CHANNEL_OPEN);
 	ssh2_pkt_addstring(pktout, "direct-tcpip");
 	ssh2_pkt_adduint32(pktout, c->localid);
+	c->throttling_conn = FALSE;
 	c->v.v2.locwindow = c->v.v2.locmaxwin = OUR_V2_WINSIZE;
 	c->v.v2.remlocwin = OUR_V2_WINSIZE;
 	c->v.v2.winadj_head = c->v.v2.winadj_head = NULL;