diff --git a/tests/core/pyspec/eth2spec/test/helpers/deposits.py b/tests/core/pyspec/eth2spec/test/helpers/deposits.py
index dae05c2eb..18929b1d7 100644
--- a/tests/core/pyspec/eth2spec/test/helpers/deposits.py
+++ b/tests/core/pyspec/eth2spec/test/helpers/deposits.py
@@ -137,14 +137,21 @@ def prepare_random_genesis_deposits(spec,
     return deposits, root, deposit_data_list
 
 
-def prepare_state_and_deposit(spec, state, validator_index, amount, withdrawal_credentials=None, signed=False):
+def prepare_state_and_deposit(spec, state, validator_index, amount,
+                              pubkey=None,
+                              privkey=None,
+                              withdrawal_credentials=None,
+                              signed=False):
     """
     Prepare the state for the deposit, and create a deposit for the given validator, depositing the given amount.
     """
     deposit_data_list = []
 
-    pubkey = pubkeys[validator_index]
-    privkey = privkeys[validator_index]
+    if pubkey is None:
+        pubkey = pubkeys[validator_index]
+
+    if privkey is None:
+        privkey = privkeys[validator_index]
 
     # insecurely use pubkey as withdrawal key if no credentials provided
     if withdrawal_credentials is None:
@@ -196,7 +203,7 @@ def run_deposit_processing(spec, state, deposit, validator_index, valid=True, ef
 
     yield 'post', state
 
-    if not effective:
+    if not effective or not bls.KeyValidate(deposit.data.pubkey):
         assert len(state.validators) == pre_validator_count
         assert len(state.balances) == pre_validator_count
         if validator_index < pre_validator_count:
diff --git a/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_deposit.py b/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_deposit.py
index df0bd2a17..f1a27f8ec 100644
--- a/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_deposit.py
+++ b/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_deposit.py
@@ -233,3 +233,17 @@ def test_bad_merkle_proof(spec, state):
     sign_deposit_data(spec, deposit.data, privkeys[validator_index])
 
     yield from run_deposit_processing(spec, state, deposit, validator_index, valid=False)
+
+
+@with_all_phases
+@spec_state_test
+def test_key_validate_invalid(spec, state):
+    validator_index = len(state.validators)
+    amount = spec.MAX_EFFECTIVE_BALANCE
+
+    # All-zero pubkey would not pass `bls.KeyValidate`, but `process_deposit` would not throw exception.
+    pubkey = b'\x00' * 48
+
+    deposit = prepare_state_and_deposit(spec, state, validator_index, amount, pubkey=pubkey, signed=True)
+
+    yield from run_deposit_processing(spec, state, deposit, validator_index)
diff --git a/tests/core/pyspec/eth2spec/utils/bls.py b/tests/core/pyspec/eth2spec/utils/bls.py
index e33017ade..fd5fd89bf 100644
--- a/tests/core/pyspec/eth2spec/utils/bls.py
+++ b/tests/core/pyspec/eth2spec/utils/bls.py
@@ -138,3 +138,8 @@ def pairing_check(values):
         * pairing(p_q_2[1], p_q_2[0], final_exponentiate=False)
     )
     return final_exponentiation == FQ12.one()
+
+
+@only_with_bls(alt_return=True)
+def KeyValidate(pubkey):
+    return py_ecc_bls.KeyValidate(pubkey)