diff --git a/src/include/lwip/tcp.h b/src/include/lwip/tcp.h
index 7b7aa17c..dcd75e30 100644
--- a/src/include/lwip/tcp.h
+++ b/src/include/lwip/tcp.h
@@ -217,7 +217,7 @@ struct tcp_pcb {
   u8_t polltmr, pollinterval;
   
   /* Retransmission timer. */
-  u8_t rtime;
+  u16_t rtime;
   
   u16_t mss;   /* maximum segment size */