diff --git a/ssh2connection.c b/ssh2connection.c
index 1a40ca7e..925b5ec9 100644
--- a/ssh2connection.c
+++ b/ssh2connection.c
@@ -535,6 +535,17 @@ static bool ssh2_connection_filter_queue(struct ssh2_connection_state *s)
                         c->chan, ext_type == SSH2_EXTENDED_DATA_STDERR,
                         data.ptr, data.len);
 
+                    /*
+                     * The channel may have turned into a connection-
+                     * shared one as a result of that chan_send, e.g.
+                     * if the data we just provided completed the X11
+                     * auth phase and caused a callback to
+                     * x11_sharing_handover. If so, do nothing
+                     * further.
+                     */
+                    if (c->sharectx)
+                        break;
+
                     /*
                      * If it looks like the remote end hit the end of
                      * its window, and we didn't want it to do that,