diff --git a/ssh.c b/ssh.c
index 421315e4..d74a0ff2 100644
--- a/ssh.c
+++ b/ssh.c
@@ -865,6 +865,13 @@ bool ssh_is_bare(Ssh *ssh)
     return ssh->backend.vt->protocol == PROT_SSHCONN;
 }
 
+/* Dummy connlayer must provide ssh_sharing_no_more_downstreams,
+ * because it might be called early due to plink -shareexists */
+static void dummy_sharing_no_more_downstreams(ConnectionLayer *cl) {}
+static const ConnectionLayerVtable dummy_connlayer_vtable = {
+    .sharing_no_more_downstreams = dummy_sharing_no_more_downstreams,
+};
+
 /*
  * Called to set up the connection.
  *
@@ -900,6 +907,7 @@ static char *ssh_init(const BackendVtable *vt, Seat *seat,
     ssh->bare_connection = (vt->protocol == PROT_SSHCONN);
 
     ssh->seat = seat;
+    ssh->cl_dummy.vt = &dummy_connlayer_vtable;
     ssh->cl_dummy.logctx = ssh->logctx = logctx;
 
     random_ref(); /* do this now - may be needed by sharing setup code */
diff --git a/ssh2connection.c b/ssh2connection.c
index 1c9454cb..ecb421ea 100644
--- a/ssh2connection.c
+++ b/ssh2connection.c
@@ -1020,6 +1020,7 @@ static void ssh2_connection_process_queue(PacketProtocolLayer *ppl)
     s->mainchan = mainchan_new(
         &s->ppl, &s->cl, s->conf, s->term_width, s->term_height,
         s->ssh_is_simple, &s->mainchan_sc);
+    s->started = true;
 
     /*
      * Transfer data!
@@ -1248,6 +1249,15 @@ static void ssh2_check_termination(struct ssh2_connection_state *s)
     if (s->persistent)
         return;     /* persistent mode: never proactively terminate */
 
+    if (!s->started) {
+        /* At startup, we don't have any channels open because we
+         * haven't got round to opening the main one yet. In that
+         * situation, we don't want to terminate, even if a sharing
+         * connection opens and closes and causes a call to this
+         * function. */
+        return;
+    }
+
     if (count234(s->channels) == 0 &&
         !(s->connshare && share_ndownstreams(s->connshare) > 0)) {
         /*
diff --git a/ssh2connection.h b/ssh2connection.h
index f0afb676..d3bb240a 100644
--- a/ssh2connection.h
+++ b/ssh2connection.h
@@ -19,6 +19,7 @@ struct ssh2_connection_state {
 
     bool ssh_is_simple;
     bool persistent;
+    bool started;
 
     Conf *conf;