diff --git a/scapy/contrib/opc_da.py b/scapy/contrib/opc_da.py
index 49bb3dec63a..42a4f67084b 100644
--- a/scapy/contrib/opc_da.py
+++ b/scapy/contrib/opc_da.py
@@ -37,6 +37,7 @@
     ConditionalField,
     Field,
     FieldLenField,
+    FieldListField,
     FlagsField,
     IntEnumField,
     IntField,
@@ -404,7 +405,7 @@ class STDOBJREF(Packet):
         LEIntField('cPublicRefs', 0),
         LELongField('OXID', 0),
         LELongField('OID', 0),
-        PacketField('IPID', None, UUIDField),
+        UUIDField('IPID', None, uuid_fmt=UUIDField.FORMAT_LE),
     ]
 
 
@@ -883,8 +884,8 @@ class OpcDaFack(Packet):
         IntField('maxFragSize', 0),
         ShortField('serialNum', 0),
         FieldLenField('selackLen', 0, count_of='selack', fmt="H"),
-        PacketListField('selack', None, IntField,
-                        count_from=lambda pkt:pkt.selackLen),
+        FieldListField('selack', [], IntField('', 0),
+                       count_from=lambda pkt: pkt.selackLen),
     ]
 
     def extract_padding(self, p):
diff --git a/test/contrib/opc_da.uts b/test/contrib/opc_da.uts
index c664a6ede74..7c55e7cc1ea 100644
--- a/test/contrib/opc_da.uts
+++ b/test/contrib/opc_da.uts
@@ -110,9 +110,18 @@ assert  elem1 == elem2
 # OpcDaCl_cancel
 # OpcDaCl_cancelLE
 
-# + Test Fack Packet
-# No example yet
-# OpcDaFack
++ Test Fack Packet
+= OpcDaFack
+opcDaFackPacket_Dissect = hex_bytes(b'0000000010000010000000080000010002aaaaaaaabbbbbbbb')
+fack = OpcDaFack(opcDaFackPacket_Dissect)
+assert fack.selackLen == 2
+assert fack.selack == [0xaaaaaaaa, 0xbbbbbbbb]
+assert raw(fack) == opcDaFackPacket_Dissect
+
+= OpcDaFackLE
+fackLE = OpcDaFackLE(opcDaFackPacket_Dissect)
+assert len(fackLE.selack) == 2
+assert raw(fackLE) == opcDaFackPacket_Dissect
 
 # + Test Cancel ack Packet
 # No example yet
@@ -180,3 +189,12 @@ elem2 = raw(ocDaAlter_contextLEPacket_Build)
 # + Test Orphaned Packet
 # No example yet
 # OpcDaOrphaned
+
++ Test STDOBJREF
+= STDOBJREF dissection
+stdObjRef_Dissect = hex_bytes(b'0100000002000000112233445566778899aabbccddeeff000102030405060708090a0b0c0d0e0f10')
+std = STDOBJREF(stdObjRef_Dissect)
+assert std.flags == 1
+assert std.cPublicRefs == 2
+assert str(std.IPID) == '04030201-0605-0807-090a-0b0c0d0e0f10'
+assert raw(std) == stdObjRef_Dissect