diff --git a/tcp_syni.nim b/tcp_syni.nim
index 90146e4..0060ca0 100644
--- a/tcp_syni.nim
+++ b/tcp_syni.nim
@@ -141,6 +141,7 @@ proc findConnectAttempt(puncher: TcpSyniPuncher, srcIp: IpAddress,
        attempt.dstIp == dstIp and
        attempt.dstPorts.any(proc (p: Port): bool = p in dstPorts):
       return index
+  return -1
 
 proc findAcceptAttempt(puncher: TcpSyniPuncher, srcIp: IpAddress,
                        srcPort: Port, dstIp: IpAddress,
@@ -150,6 +151,7 @@ proc findAcceptAttempt(puncher: TcpSyniPuncher, srcIp: IpAddress,
        attempt.dstIp == dstIp and
        attempt.dstPorts.any(proc (p: Port): bool = p in dstPorts):
       return index
+  return -1
 
 proc findAcceptAttemptsByLocalAddr(puncher: TcpSyniPuncher, address: IpAddress,
                                    port: Port): seq[AcceptAttempt] =