diff --git a/core/net/uip6.c b/core/net/uip6.c
index e79486ff1..7f51ce4e9 100644
--- a/core/net/uip6.c
+++ b/core/net/uip6.c
@@ -1833,8 +1833,12 @@ uip_process(uint8_t flag)
         UIP_TCP_BUF->seqno[2] != uip_connr->rcv_nxt[2] ||
         UIP_TCP_BUF->seqno[3] != uip_connr->rcv_nxt[3])) {
 
-      if(UIP_TCP_BUF->flags & TCP_SYN) {
-        goto tcp_send_synack;
+      if((UIP_TCP_BUF->flags & TCP_SYN)) {
+        if((uip_connr->tcpstateflags & UIP_TS_MASK) == UIP_SYN_RCVD) {
+          goto tcp_send_synack;
+        } else if((uip_connr->tcpstateflags & UIP_TS_MASK) == UIP_SYN_SENT) {
+          goto tcp_send_syn;
+        }
       }
       goto tcp_send_ack;
     }