diff --git a/src/include/ipv4/lwip/inet.h b/src/include/ipv4/lwip/inet.h
index 0d8169e0..6d79aab7 100644
--- a/src/include/ipv4/lwip/inet.h
+++ b/src/include/ipv4/lwip/inet.h
@@ -39,7 +39,7 @@
 #include "lwip/ip_addr.h"
 
 u16_t inet_chksum(void *dataptr, u16_t len);
-#if 0 // optimized routine
+#if 0 /* optimized routine */
 u16_t inet_chksum4(u8_t *dataptr, u16_t len);
 #endif
 u16_t inet_chksum_pbuf(struct pbuf *p);