diff --git a/src/netif/ppp/eui64.c b/src/netif/ppp/eui64.c
index e23a34e8..e042eb4c 100644
--- a/src/netif/ppp/eui64.c
+++ b/src/netif/ppp/eui64.c
@@ -45,9 +45,9 @@
  * eui64_ntoa - Make an ascii representation of an interface identifier
  */
 char *eui64_ntoa(eui64_t e) {
-    static char buf[32];
+    static char buf[20];
 
-    snprintf(buf, 32, "%02x%02x:%02x%02x:%02x%02x:%02x%02x",
+    sprintf(buf, "%02x%02x:%02x%02x:%02x%02x:%02x%02x",
 	     e.e8[0], e.e8[1], e.e8[2], e.e8[3], 
 	     e.e8[4], e.e8[5], e.e8[6], e.e8[7]);
     return buf;
diff --git a/src/netif/ppp/ipv6cp.c b/src/netif/ppp/ipv6cp.c
index 74b0cc6a..eba006fe 100644
--- a/src/netif/ppp/ipv6cp.c
+++ b/src/netif/ppp/ipv6cp.c
@@ -412,9 +412,12 @@ printifaceid(opt, printer, arg)
 static char *
 llv6_ntoa(eui64_t ifaceid)
 {
-    static char b[64];
+    static char b[26];
+
+    sprintf(b, "fe80::%02x%02x:%02x%02x:%02x%02x:%02x%02x",
+      ifaceid.e8[0], ifaceid.e8[1], ifaceid.e8[2], ifaceid.e8[3],
+      ifaceid.e8[4], ifaceid.e8[5], ifaceid.e8[6], ifaceid.e8[7]);
 
-    sprintf(b, "fe80::%s", eui64_ntoa(ifaceid));
     return b;
 }