diff --git a/include/net.h b/include/net.h
index df86176efe..bcf396a4eb 100644
--- a/include/net.h
+++ b/include/net.h
@@ -178,7 +178,7 @@ void eth_halt(void);			/* stop SCC */
 const char *eth_get_name(void);		/* get name of current device */
 
 #ifdef CONFIG_MCAST_TFTP
-int eth_mcast_join(IPaddr_t mcast_addr, u8 join);
+int eth_mcast_join(IPaddr_t mcast_addr, int join);
 u32 ether_crc(size_t len, unsigned char const *p);
 #endif
 
diff --git a/net/eth.c b/net/eth.c
index 9ad15cd8a3..b86994e9eb 100644
--- a/net/eth.c
+++ b/net/eth.c
@@ -321,7 +321,7 @@ int eth_initialize(bd_t *bis)
  * mcast_addr: multicast ipaddr from which multicast Mac is made
  * join: 1=join, 0=leave.
  */
-int eth_mcast_join(IPaddr_t mcast_ip, u8 join)
+int eth_mcast_join(IPaddr_t mcast_ip, int join)
 {
 	u8 mcast_mac[6];
 	if (!eth_current || !eth_current->mcast)