diff --git a/tcp_syni.nim b/tcp_syni.nim
index 8649778..7b0200d 100644
--- a/tcp_syni.nim
+++ b/tcp_syni.nim
@@ -89,7 +89,8 @@ proc injectSyns(rawFd: AsyncFD, srcIp: IpAddress, srcPort: Port,
                             tcpIpDst: dstIp,
                             tcpPortSrc: dstPort,
                             tcpPortDst: srcPort,
-                            tcpSeqNumber: seqNum)
+                            tcpSeqNumber: seqNum,
+                            tcpFlags: {SYN})
     asyncCheck rawFd.send(serialize(ipPacket))
 
 proc initPuncher*(srcPort: Port, dstIp: IpAddress, dstPorts: array[3, Port],