diff --git a/net/eth_common.c b/net/eth_common.c
index 2880901..e9d3c66 100644
--- a/net/eth_common.c
+++ b/net/eth_common.c
@@ -32,7 +32,7 @@
 
 int eth_setenv_enetaddr(const char *name, const uchar *enetaddr)
 {
-	char buf[20];
+	char buf[ARP_HLEN_ASCII + 1];
 
 	sprintf(buf, "%pM", enetaddr);