diff --git a/drivers/net/mmnif.c b/drivers/net/mmnif.c
index 0d336b26..9393ab07 100644
--- a/drivers/net/mmnif.c
+++ b/drivers/net/mmnif.c
@@ -841,7 +841,7 @@ err_t mmnif_init(struct netif* netif)
 		DEBUGPRINTF("mmnif init(): allocating shared memory failed\n");
 		return ERR_MEM;
 	}
-	memset(mmnif->rx_buff, 0, sizeof(mm_rx_buffer_t) + MMNIF_RX_QUEUELEN* MMNIF_RX_BUFFERLEN);
+	memset(mmnif->rx_buff, 0, (sizeof(mm_rx_buffer_t) + MMNIF_RX_QUEUELEN* MMNIF_RX_BUFFERLEN)* MMNIF_CORES);
 
 	/* init the lock for the hdr
 	 */