diff --git a/mtcp/src/include/tcp_in.h b/mtcp/src/include/tcp_in.h
index 18cc53b..31c17ab 100644
--- a/mtcp/src/include/tcp_in.h
+++ b/mtcp/src/include/tcp_in.h
@@ -70,6 +70,8 @@
 #define TCP_MAX_SYN_RETRY		7
 #define TCP_MAX_BACKOFF			7
 
+#define TCP_INIT_CWND                   10
+
 enum tcp_state
 {
 	TCP_ST_CLOSED		= 0, 
diff --git a/mtcp/src/tcp_in.c b/mtcp/src/tcp_in.c
index e35c9d2..226bb97 100644
--- a/mtcp/src/tcp_in.c
+++ b/mtcp/src/tcp_in.c
@@ -94,7 +94,7 @@ HandleActiveOpen(mtcp_manager_t mtcp, tcp_stream *cur_stream, uint32_t cur_ts,
 	ParseTCPOptions(cur_stream, cur_ts, (uint8_t *)tcph + TCP_HEADER_LEN, 
 			(tcph->doff << 2) - TCP_HEADER_LEN);
 	cur_stream->sndvar->cwnd = ((cur_stream->sndvar->cwnd == 1)? 
-			(cur_stream->sndvar->mss * 2): cur_stream->sndvar->mss);
+			(cur_stream->sndvar->mss * TCP_INIT_CWND): cur_stream->sndvar->mss);
 	cur_stream->sndvar->ssthresh = cur_stream->sndvar->mss * 10;
 	UpdateRetransmissionTimer(mtcp, cur_stream, cur_ts);