diff --git a/pycardano/txbuilder.py b/pycardano/txbuilder.py
index bf10d1c4..c8810ae8 100644
--- a/pycardano/txbuilder.py
+++ b/pycardano/txbuilder.py
@@ -5,6 +5,7 @@
 from typing import Dict, List, Optional, Set, Tuple, Union
 
 from pycardano import RedeemerMap
+from pycardano import witness
 from pycardano.address import Address, AddressType
 from pycardano.backend.base import ChainContext
 from pycardano.certificate import (
@@ -1508,4 +1509,7 @@ def build_and_sign(
                 VerificationKeyWitness(signing_key.to_verification_key(), signature)
             )
 
+        if len(witness_set.vkey_witnesses) == 0:
+            witness_set.vkey_witnesses = None
+
         return Transaction(tx_body, witness_set, auxiliary_data=self.auxiliary_data)