diff --git a/drivers/net/mmnif.c b/drivers/net/mmnif.c
index 6ca4a96b..33fef2d8 100644
--- a/drivers/net/mmnif.c
+++ b/drivers/net/mmnif.c
@@ -417,7 +417,6 @@ static uint8_t mmnif_get_destination(struct netif *netif, struct pbuf *p)
 {
 	struct ip_hdr *iphdr;
 	ip_addr_p_t ip;
-	uint8_t core;
 
 	/* grab the destination ip address out of the ip header
 	 * for internal routing the last ocet is interpreted as core ID.
@@ -425,19 +424,7 @@ static uint8_t mmnif_get_destination(struct netif *netif, struct pbuf *p)
 	iphdr = (struct ip_hdr *)(p->payload);
 	ip = iphdr->dest;
 
-	/* check if the ip address is in the Local Area Network of the 48 cores */
-
-	/* if it's not the same network the router core is addressed 
-	 * Note: the router core is core 1
-	 */
-	if (ip_addr_netcmp(&ip, &netif->ip_addr, &netif->netmask))
-		return 1;
-	core = ip4_addr4(&ip);
-
-	/* check if the address is legitimata else return router core again */
-	if ((core) < 1 || (core > MMNIF_CORES))
-		core = 1;
-	return core;
+	return ip4_addr4(&ip);
 }
 
 /* mmnif_rxbuff_alloc():
@@ -622,6 +609,12 @@ static err_t mmnif_tx(struct netif *netif, struct pbuf *p)
 		goto drop_packet;
 	}
 
+	/* check destination ip */
+	if (BUILTIN_EXPECT((dest_ip < 1) || (dest_ip > MMNIF_CORES), 0)) {
+		DEBUGPRINTF("mmnif_tx: invalid destination IP %d => drop\n", dest_ip);
+		goto drop_packet;
+	}
+
 	/* allocate memory for the packet in the remote buffer */
 realloc:
 	write_address = mmnif_rxbuff_alloc(dest_ip, p->tot_len);