diff --git a/includes/site.h b/includes/site.h
--- a/includes/site.h
+++ b/includes/site.h
@@ -329,7 +329,7 @@
  * for IA_NA pools, if the parameter use-eui-64 is true for the
  * pool.  Can be at all scopes down to the pool level.  Not
  * supported by the configure script. */
-/* #define EUI_64 */
+#define EUI_64
 
 /* Enable enforcement of the require option statement as documented
  * in man page.  Instructs the dhclient, when in -6 mode, to discard
diff --git a/server/mdb6.c b/server/mdb6.c
--- a/server/mdb6.c
+++ b/server/mdb6.c
@@ -859,18 +859,32 @@ build_address6(struct in6_addr *addr,
 #ifdef EUI_64
 int
 valid_eui_64_duid(const struct data_string* uid, int offset) {
+	/* actual EUI-64, which dhclient does not actually use, at least by default */
+	const unsigned char* duid = uid->data + offset;
 	if (uid->len == (offset + EUI_64_ID_LEN)) {
-		const unsigned char* duid = uid->data + offset;
 		return (((duid[0] == 0x00 && duid[1] == 0x03)  &&
 			(duid[2] == 0x00 && duid[3] == 0x1b)));
 	}
-
+	/* add a hack to handle LL and LLT like they are EUI-64 */
+	if (uid->len == (offset + 4 + 6)) {
+		return (((duid[0] == 0x00 && duid[1] == 0x03)  &&
+			(duid[2] == 0x00 && duid[3] == 0x01)));
+	}
+	/* this is the LLT format, we discard the time part and consider only the mac address */
+	if (uid->len == (offset + 4 + 4 + 6)) {
+		return (((duid[0] == 0x00 && duid[1] == 0x01)  &&
+			(duid[2] == 0x00 && duid[3] == 0x01)));
+	}
     return(0);
 }
 
 
 /*
- * Create an EUI-64 address 
+ * Create an IPv6 address from EUI-64 address, or MAC (like EUI-48) address
+ * also treat LL and LLT DUID like this
+ * 0x1b = EUI-64 whereas 01 = MAC address
+ *  https://www.iana.org/assignments/arp-parameters/arp-parameters.xhtml#arp-parameters-2
+ * dhclient -6 -D LLT -d eth0
  */
 static isc_result_t
 build_address6_eui_64(struct in6_addr *addr,
@@ -884,19 +898,38 @@ build_address6_eui_64(struct in6_addr *addr,
 
 	if (valid_eui_64_duid(iaid_duid, duid_beg)) {
 		const unsigned char *duid = iaid_duid->data + duid_beg;
-
 		/* copy network prefix to the high 64 bits */
 		memcpy(addr->s6_addr, net_start_addr->s6_addr, 8);
 
-		/* copy Link-layer address to low 64 bits */
-		memcpy(addr->s6_addr + 8, duid + 4, 8);
+		if (duid[3] == 0x1b) {
+			/* copy Link-layer address to low 64 bits */
+			memcpy(addr->s6_addr + 8, duid + 4, 8);
+		}
+		if (duid[3] == 0x01) {
+			if (duid[1] == 0x03) {
+				/* copy OUI part of mac address */
+				memcpy(addr->s6_addr + 8, duid + 4, 3);
+
+				/* copy vendor part of mac address */
+				memcpy(addr->s6_addr + 8 + 3 + 2, duid + 7, 3);
+			}
+			if (duid[1] == 0x01) {
+				/* copy OUI part of mac address */
+				memcpy(addr->s6_addr + 8, duid + 4 + 4, 3);
+
+				/* copy vendor part of mac address */
+				memcpy(addr->s6_addr + 8 + 3 + 2, duid + 4 + 7, 3);
+			}
+			addr->s6_addr[11] = 0xff;
+			addr->s6_addr[12] = 0xfe;
+		}
 
 		/* RFC-3315 Any address assigned by a server that is based
 		 * on an EUI-64 identifier MUST include an interface identifier
 		 * with the "u" (universal/local) and "g" (individual/group)
 		 * bits of the interface identifier set appropriately, as
 		 * indicated in section 2.5.1 of RFC 2373 [5]. */
-		addr->s6_addr[8] |= 0x02;
+		addr->s6_addr[8] ^= 0x02;
 		return (ISC_R_SUCCESS);
 	}
 
-- 
2.30.2