diff --git a/src/tcp.c b/src/tcp.c
index 438d22b..d029c9d 100644
--- a/src/tcp.c
+++ b/src/tcp.c
@@ -44,7 +44,7 @@
  * @return	0 for success
  * @return	1 for failure
  */
-int tcp_ipv4(struct s_ethernet *eth, struct s_ipv4 *ip4, char *payload,
+int tcp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4, char *payload,
 	     unsigned short payload_size)
 {
 	struct s_tcp  *tcp;
@@ -141,7 +141,7 @@ int tcp_ipv4(struct s_ethernet *eth, struct s_ipv4 *ip4, char *payload,
  * @return	0 for success
  * @return	1 for failure
  */
-int tcp_ipv6(struct s_ethernet *eth, struct s_ipv6 *ip6, char *payload)
+int tcp_ipv6(struct s_ethernet *eth6, struct s_ipv6 *ip6, char *payload)
 {
 	struct s_tcp  *tcp;
 	struct s_nat  *connection;
@@ -167,7 +167,7 @@ int tcp_ipv6(struct s_ethernet *eth, struct s_ipv6 *ip6, char *payload)
 	}
 
 	/* find connection in NAT */
-	connection = nat_out(nat6_tcp, nat4_tcp, eth->src,
+	connection = nat_out(nat6_tcp, nat4_tcp, eth6->src,
 			     ip6->ip_src, ip6->ip_dest,
 			     tcp->port_src, tcp->port_dest);
 
diff --git a/src/tcp.h b/src/tcp.h
index a5f51cd..dbcde8a 100644
--- a/src/tcp.h
+++ b/src/tcp.h
@@ -33,8 +33,8 @@ struct s_tcp {
 	unsigned short urgent_ptr;	/* 16 b; ptr to last urgent data byte */
 } __attribute__ ((__packed__));
 
-int tcp_ipv4(struct s_ethernet *eth, struct s_ipv4 *ip4, char *payload,
+int tcp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4, char *payload,
 	     unsigned short payload_size);
-int tcp_ipv6(struct s_ethernet *eth, struct s_ipv6 *ip6, char *payload);
+int tcp_ipv6(struct s_ethernet *eth6, struct s_ipv6 *ip6, char *payload);
 
 #endif /* TCP_H */
diff --git a/src/udp.c b/src/udp.c
index a64a25d..bbaff41 100644
--- a/src/udp.c
+++ b/src/udp.c
@@ -44,7 +44,7 @@
  * @return	0 for success
  * @return	1 for failure
  */
-int udp_ipv4(struct s_ethernet *eth, struct s_ipv4 *ip4, char *payload,
+int udp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4, char *payload,
 	     unsigned short payload_size)
 {
 	struct s_udp  *udp;
@@ -147,7 +147,7 @@ int udp_ipv4(struct s_ethernet *eth, struct s_ipv4 *ip4, char *payload,
  * @return	0 for success
  * @return	1 for failure
  */
-int udp_ipv6(struct s_ethernet *eth, struct s_ipv6 *ip6, char *payload)
+int udp_ipv6(struct s_ethernet *eth6, struct s_ipv6 *ip6, char *payload)
 {
 	struct s_udp  *udp;
 	struct s_nat  *connection;
@@ -173,7 +173,7 @@ int udp_ipv6(struct s_ethernet *eth, struct s_ipv6 *ip6, char *payload)
 	}
 
 	/* find connection in NAT */
-	connection = nat_out(nat6_udp, nat4_udp, eth->src,
+	connection = nat_out(nat6_udp, nat4_udp, eth6->src,
 			     ip6->ip_src, ip6->ip_dest,
 			     udp->port_src, udp->port_dest);
 
diff --git a/src/udp.h b/src/udp.h
index 3513f18..7e5aab5 100644
--- a/src/udp.h
+++ b/src/udp.h
@@ -27,8 +27,8 @@ struct s_udp {
 	unsigned short checksum;	/* 16 b; optional checksum */
 } __attribute__ ((__packed__));
 
-int udp_ipv4(struct s_ethernet *eth, struct s_ipv4 *ip4, char *payload,
+int udp_ipv4(struct s_ethernet *eth4, struct s_ipv4 *ip4, char *payload,
 	     unsigned short payload_size);
-int udp_ipv6(struct s_ethernet *eth, struct s_ipv6 *ip6, char *payload);
+int udp_ipv6(struct s_ethernet *eth6, struct s_ipv6 *ip6, char *payload);
 
 #endif /* UDP_H */