diff --git a/libports/include/lwip/lwipopts.h b/libports/include/lwip/lwipopts.h
index d4dea2e54d..c3af641afe 100644
--- a/libports/include/lwip/lwipopts.h
+++ b/libports/include/lwip/lwipopts.h
@@ -49,6 +49,19 @@
 #define TCP_MSS                  1460
 #define TCP_SND_BUF     (2 * TCP_MSS)
 
+/*
+ * We reduce the maximum segment lifetime from one minute to one second to
+ * avoid queuing up PCBs in TIME-WAIT state. This is the state, PCBs end up
+ * after closing a TCP connection socket at the server side. The number of PCBs
+ * in this state is apparently not limited by the value of 'MEMP_NUM_TCP_PCB'.
+ * One allocation costs around 160 bytes. If clients connect to the server at a
+ * high rate, those allocations accumulate quickly and thereby may exhaust the
+ * memory of the server. By reducing the segment lifetime, PCBs in TIME-WAIT
+ * state are cleaned up from the 'tcp_tw_pcbs' queue in a more timely fashion
+ * (by 'tcp_slowtmr()').
+ */
+#define TCP_MSL 1000UL
+
 #define MEMP_NUM_SYS_TIMEOUT        8
 #define MEMP_NUM_TCP_PCB           64
 #define MEMP_NUM_NETCONN (MEMP_NUM_TCP_PCB + MEMP_NUM_UDP_PCB + MEMP_NUM_RAW_PCB + MEMP_NUM_TCP_PCB_LISTEN - 1)