diff --git a/test_libs/pyspec/eth2spec/test/block_processing/test_process_deposit.py b/test_libs/pyspec/eth2spec/test/block_processing/test_process_deposit.py
index 0ef2e509a..0430dd12f 100644
--- a/test_libs/pyspec/eth2spec/test/block_processing/test_process_deposit.py
+++ b/test_libs/pyspec/eth2spec/test/block_processing/test_process_deposit.py
@@ -94,6 +94,22 @@ def test_invalid_sig_top_up(state):
     yield from run_deposit_processing(state, deposit, validator_index, valid=True, effective=True)
 
 
+@spec_state_test
+def test_invalid_withdrawal_credentials_top_up(state):
+    validator_index = 0
+    amount = spec.MAX_EFFECTIVE_BALANCE // 4
+    withdrawal_credentials = spec.BLS_WITHDRAWAL_PREFIX_BYTE + spec.hash(b"junk")[1:]
+    deposit = prepare_state_and_deposit(
+        state,
+        validator_index,
+        amount,
+        withdrawal_credentials=withdrawal_credentials
+    )
+
+    # inconsistent withdrawal credentials, in top-ups, are allowed!
+    yield from run_deposit_processing(state, deposit, validator_index, valid=True, effective=True)
+
+
 @spec_state_test
 def test_wrong_index(state):
     validator_index = len(state.validator_registry)
@@ -122,6 +138,7 @@ def test_wrong_deposit_for_deposit_count(state):
         pubkey_1,
         privkey_1,
         spec.MAX_EFFECTIVE_BALANCE,
+        withdrawal_credentials=b'\x00'*32,
         signed=True,
     )
     deposit_count_1 = len(deposit_data_leaves)
@@ -136,6 +153,7 @@ def test_wrong_deposit_for_deposit_count(state):
         pubkey_2,
         privkey_2,
         spec.MAX_EFFECTIVE_BALANCE,
+        withdrawal_credentials=b'\x00'*32,
         signed=True,
     )
 
diff --git a/test_libs/pyspec/eth2spec/test/helpers/deposits.py b/test_libs/pyspec/eth2spec/test/helpers/deposits.py
index c5deb124e..2db3ae03c 100644
--- a/test_libs/pyspec/eth2spec/test/helpers/deposits.py
+++ b/test_libs/pyspec/eth2spec/test/helpers/deposits.py
@@ -8,11 +8,10 @@ from eth2spec.utils.merkle_minimal import calc_merkle_tree_from_leaves, get_merk
 from eth2spec.utils.minimal_ssz import signing_root
 
 
-def build_deposit_data(state, pubkey, privkey, amount, signed=False):
+def build_deposit_data(state, pubkey, privkey, amount, withdrawal_credentials, signed=False):
     deposit_data = DepositData(
         pubkey=pubkey,
-        # insecurely use pubkey as withdrawal key as well
-        withdrawal_credentials=spec.BLS_WITHDRAWAL_PREFIX_BYTE + spec.hash(pubkey)[1:],
+        withdrawal_credentials=withdrawal_credentials,
         amount=amount,
     )
     if signed:
@@ -37,8 +36,9 @@ def build_deposit(state,
                   pubkey,
                   privkey,
                   amount,
+                  withdrawal_credentials,
                   signed):
-    deposit_data = build_deposit_data(state, pubkey, privkey, amount, signed)
+    deposit_data = build_deposit_data(state, pubkey, privkey, amount, withdrawal_credentials, signed)
 
     item = deposit_data.hash_tree_root()
     index = len(deposit_data_leaves)
@@ -57,7 +57,7 @@ def build_deposit(state,
     return deposit, root, deposit_data_leaves
 
 
-def prepare_state_and_deposit(state, validator_index, amount, signed=False):
+def prepare_state_and_deposit(state, validator_index, amount, withdrawal_credentials=None, signed=False):
     """
     Prepare the state for the deposit, and create a deposit for the given validator, depositing the given amount.
     """
@@ -67,12 +67,18 @@ def prepare_state_and_deposit(state, validator_index, amount, signed=False):
 
     pubkey = pubkeys[validator_index]
     privkey = privkeys[validator_index]
+
+    # insecurely use pubkey as withdrawal key if no credentials provided
+    if withdrawal_credentials is None:
+        withdrawal_credentials = spec.BLS_WITHDRAWAL_PREFIX_BYTE + spec.hash(pubkey)[1:]
+
     deposit, root, deposit_data_leaves = build_deposit(
         state,
         deposit_data_leaves,
         pubkey,
         privkey,
         amount,
+        withdrawal_credentials,
         signed
     )