diff --git a/tcp_syni.nim b/tcp_syni.nim
index 7b0200d..803ceb2 100644
--- a/tcp_syni.nim
+++ b/tcp_syni.nim
@@ -72,8 +72,7 @@ proc captureSeqNumbers(puncher: TcpSyniPuncher, rawFd: AsyncFD,
        parsed.tcpIpSrc == puncher.srcIp and
        parsed.tcpPortSrc.int == puncher.srcPort.int and
        parsed.tcpIpDst == puncher.dstIp and
-       parsed.tcpFlags.contains(SYN) and
-       not parsed.tcpFlags.contains(ACK):
+       parsed.tcpFlags == {SYN}:
       for i, port in puncher.dstPorts.pairs:
         if parsed.tcpPortDst.int == port.int:
           seqNums.add(parsed.tcpSeqNumber)