diff --git a/ssh.h b/ssh.h
index c5c8cdb9..2858a14a 100644
--- a/ssh.h
+++ b/ssh.h
@@ -236,6 +236,9 @@ struct ConnectionLayerVtable {
     void (*sharing_queue_global_request)(
         ConnectionLayer *cl, ssh_sharing_connstate *connstate);
 
+    /* Indicate that the last downstream has disconnected */
+    void (*sharing_no_more_downstreams)(ConnectionLayer *cl);
+
     /* Query whether the connection layer is doing agent forwarding */
     int (*agent_forwarding_permitted)(ConnectionLayer *cl);
 
@@ -281,6 +284,8 @@ struct ConnectionLayer {
     ((cl)->vt->delete_sharing_channel(cl, ch))
 #define ssh_sharing_queue_global_request(cl, cs) \
     ((cl)->vt->sharing_queue_global_request(cl, cs))
+#define ssh_sharing_no_more_downstreams(cl) \
+    ((cl)->vt->sharing_no_more_downstreams(cl))
 #define ssh_agent_forwarding_permitted(cl) \
     ((cl)->vt->agent_forwarding_permitted(cl))
 #define ssh_terminal_size(cl, w, h) ((cl)->vt->terminal_size(cl, w, h))
diff --git a/ssh1connection.c b/ssh1connection.c
index 3ae36bd3..86e16f90 100644
--- a/ssh1connection.c
+++ b/ssh1connection.c
@@ -119,6 +119,7 @@ static const struct ConnectionLayerVtable ssh1_connlayer_vtable = {
     NULL /* alloc_sharing_channel */,
     NULL /* delete_sharing_channel */,
     NULL /* sharing_queue_global_request */,
+    NULL /* sharing_no_more_downstreams */,
     ssh1_agent_forwarding_permitted,
     ssh1_terminal_size,
     ssh1_stdout_unthrottle,
diff --git a/ssh2connection.c b/ssh2connection.c
index ea03f575..71dd1007 100644
--- a/ssh2connection.c
+++ b/ssh2connection.c
@@ -127,6 +127,7 @@ static void ssh2_delete_sharing_channel(
     ConnectionLayer *cl, unsigned localid);
 static void ssh2_sharing_queue_global_request(
     ConnectionLayer *cl, ssh_sharing_connstate *share_ctx);
+static void ssh2_sharing_no_more_downstreams(ConnectionLayer *cl);
 static int ssh2_agent_forwarding_permitted(ConnectionLayer *cl);
 static void ssh2_terminal_size(ConnectionLayer *cl, int width, int height);
 static void ssh2_stdout_unthrottle(ConnectionLayer *cl, int bufsize);
@@ -144,6 +145,7 @@ static const struct ConnectionLayerVtable ssh2_connlayer_vtable = {
     ssh2_alloc_sharing_channel,
     ssh2_delete_sharing_channel,
     ssh2_sharing_queue_global_request,
+    ssh2_sharing_no_more_downstreams,
     ssh2_agent_forwarding_permitted,
     ssh2_terminal_size,
     ssh2_stdout_unthrottle,
@@ -2096,6 +2098,13 @@ static void ssh2_sharing_queue_global_request(
     ssh2_queue_global_request_handler(s, ssh2_sharing_globreq_response, cs);
 }
 
+static void ssh2_sharing_no_more_downstreams(ConnectionLayer *cl)
+{
+    struct ssh2_connection_state *s =
+        FROMFIELD(cl, struct ssh2_connection_state, cl);
+    queue_toplevel_callback(ssh2_check_termination_callback, s);
+}
+
 static struct X11FakeAuth *ssh2_add_sharing_x11_display(
     ConnectionLayer *cl, int authtype, ssh_sharing_connstate *share_cs,
     share_channel *share_chan)
diff --git a/sshshare.c b/sshshare.c
index 937b4da6..c425140a 100644
--- a/sshshare.c
+++ b/sshshare.c
@@ -905,12 +905,22 @@ static void share_try_cleanup(struct ssh_sharing_connstate *cs)
     if (count234(cs->halfchannels) == 0 &&
         count234(cs->channels_by_us) == 0 &&
         count234(cs->forwardings) == 0) {
+        struct ssh_sharing_state *sharestate = cs->parent;
+
         /*
          * Now we're _really_ done, so we can get rid of cs completely.
          */
-        del234(cs->parent->connections, cs);
+        del234(sharestate->connections, cs);
         log_downstream(cs, "disconnected");
         share_connstate_free(cs);
+
+        /*
+         * And if this was the last downstream, notify the connection
+         * layer, because it might now be time to wind up the whole
+         * SSH connection.
+         */
+        if (count234(sharestate->connections) == 0 && sharestate->cl)
+            ssh_sharing_no_more_downstreams(sharestate->cl);
     }
 }