diff --git a/src/include/lwip/tcp.h b/src/include/lwip/tcp.h
index 1454abdb..e6b6a292 100644
--- a/src/include/lwip/tcp.h
+++ b/src/include/lwip/tcp.h
@@ -272,7 +272,7 @@ struct tcp_pcb {
 #endif /* LWIP_TCP_KEEPALIVE */
   
   /* Persist timer counter */
-  u32_t persist_cnt;
+  u8_t persist_cnt;
   /* Persist timer back-off */
   u8_t persist_backoff;