diff --git a/internal/dhcpd/routeradv.go b/internal/dhcpd/routeradv.go
index 9c87ca9f..f2cdd561 100644
--- a/internal/dhcpd/routeradv.go
+++ b/internal/dhcpd/routeradv.go
@@ -49,18 +49,20 @@ func hwAddrToLinkLayerAddr(hwa net.HardwareAddr) (lla []byte, err error) {
 		return nil, err
 	}
 
-	if len(hwa) == 6 || len(hwa) == 8 {
-		lla = make([]byte, 8)
-		copy(lla, hwa)
+	switch len(hwa) {
+	// EUI-48 are 6 bytes, so 6 + 2 prefix bytes is divisible by 8
+	case 6:
+		lla = make([]byte, 6)
 
-		return lla, nil
+	// EUI-64 are 8 bytes, so pad to 14 so that with the prefix, it's divisible by 8
+	case 8:
+		lla = make([]byte, 14)
+
+	// The last validated type by netutil.ValidateMAC is 20 byte InfiniBand link-layer address
+	default:
+		lla = make([]byte, 22)
 	}
-
-	// Assume that netutil.ValidateMAC prevents lengths other than 20 by
-	// now.
-	lla = make([]byte, 24)
 	copy(lla, hwa)
-
 	return lla, nil
 }
 
@@ -92,7 +94,9 @@ func hwAddrToLinkLayerAddr(hwa net.HardwareAddr) (lla []byte, err error) {
 //	    - Reserved[2]
 //	    - MTU[4]
 //	  - Option=Source link-layer address(1):
-//	    - Link-Layer Address[8/24]
+//	    - Type[1]
+//	    - Length * 8bytes[1]
+//	    - Link-Layer Address[6/14/22]
 //	  - Option=Recursive DNS Server(25):
 //	    - Type[1]
 //	    - Length * 8bytes[1]
diff --git a/internal/dhcpd/routeradv_test.go b/internal/dhcpd/routeradv_test.go
index 94f7afd3..e007d460 100644
--- a/internal/dhcpd/routeradv_test.go
+++ b/internal/dhcpd/routeradv_test.go
@@ -17,10 +17,9 @@ func TestCreateICMPv6RAPacket(t *testing.T) {
 		0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 		0x05, 0x01, 0x00, 0x00, 0x00, 0x00, 0x05, 0xdc,
 		0x01, 0x01, 0x0a, 0x00, 0x27, 0x00, 0x00, 0x00,
-		0x00, 0x00, 0x19, 0x03, 0x00, 0x00, 0x00, 0x00,
-		0x0e, 0x10, 0xfe, 0x80, 0x00, 0x00, 0x00, 0x00,
-		0x00, 0x00, 0x08, 0x00, 0x27, 0xff, 0xfe, 0x00,
-		0x00, 0x00,
+		0x19, 0x03, 0x00, 0x00, 0x00, 0x00, 0x0e, 0x10,
+		0xfe, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+		0x08, 0x00, 0x27, 0xff, 0xfe, 0x00, 0x00, 0x00,
 	}
 
 	gotData, err := createICMPv6RAPacket(icmpv6RA{