diff --git a/libs/ardour/session_ltc.cc b/libs/ardour/session_ltc.cc
index 8acb16dde3..0cd365e117 100644
--- a/libs/ardour/session_ltc.cc
+++ b/libs/ardour/session_ltc.cc
@@ -176,6 +176,21 @@ Session::ltc_tx_send_time_code_for_cycle (framepos_t start_frame, framepos_t end
 		return;
 	}
 
+#if 1
+	/* Work around a race-condition on Windows/ PortAudio.
+	 * It may happen that we do have a valid ltcport (created
+	 * with the session), but no valid port-handle yet:
+	 *
+	 * Session > New implicitly closes old session and creates
+	 * a new session directly after.
+	 * re-registers ports fail? delayed? first proc callback only?
+	 * reason is still unknown
+	 */
+	if (!ltcport->port_handle ()) {
+		return;
+	}
+#endif
+
 	/* marks buffer as not written */
 	Buffer& buf (ltcport->get_buffer (nframes));