diff --git a/src/flt_spoe.c b/src/flt_spoe.c
index c256303..7a19a18 100644
--- a/src/flt_spoe.c
+++ b/src/flt_spoe.c
@@ -1030,6 +1030,8 @@
 		    (unsigned int)stream_id, (unsigned int)frame_id);
 
 	SPOE_APPCTX(appctx)->status_code = SPOE_FRM_ERR_FRAMEID_NOTFOUND;
+	if (appctx->st0 == SPOE_APPCTX_ST_WAITING_SYNC_ACK)
+		return -1;
 	return 0;
 
   found: