diff --git a/src/evm_transition_tool/geth.py b/src/evm_transition_tool/geth.py
index 251b699d03..50a73aca2f 100644
--- a/src/evm_transition_tool/geth.py
+++ b/src/evm_transition_tool/geth.py
@@ -13,7 +13,7 @@
 from re import compile
 from typing import Dict, Optional
 
-from ethereum_test_base_types import Address, Alloc, to_json
+from ethereum_test_base_types import Address, Alloc, ZeroPaddedHexNumber, to_json
 from ethereum_test_forks import Fork
 from ethereum_test_types.verkle import VerkleTree, WitnessCheck
 from ethereum_test_types.verkle.types import Hash as VerkleHash
@@ -191,7 +191,9 @@ def get_verkle_state_root(self, mpt_alloc: Alloc) -> bytes:
             hex_string = self._run_verkle_command("state-root", "--input.alloc", alloc_path)
             return binascii.unhexlify(hex_string[2:])
 
-    def get_verkle_single_key(self, address: Address, storage_slot: Optional[int] = None) -> str:
+    def get_verkle_single_key(
+        self, address: Address, storage_slot: Optional[ZeroPaddedHexNumber] = None
+    ) -> str:
         """
         Returns the VKT key for an account address or storage slot.
         """
@@ -199,14 +201,14 @@ def get_verkle_single_key(self, address: Address, storage_slot: Optional[int] =
         if storage_slot is not None:
             args.append(str(storage_slot))
         output = self._run_verkle_command("single-key", *args)
-        return str(json.loads(output))
+        return output
 
-    def get_verkle_code_chunk_key(self, address: Address, code_chunk: int) -> str:
+    def get_verkle_code_chunk_key(self, address: Address, code_chunk: ZeroPaddedHexNumber) -> str:
         """
         Returns the VKT key of a code chunk for an account address.
         """
         output = self._run_verkle_command("code-chunk-key", str(address), str(code_chunk))
-        return str(json.loads(output))
+        return output
 
     def format_witness_check(
         self, witness_check: WitnessCheck
@@ -228,13 +230,17 @@ def format_witness_check(
         # Format storage entries using `evm verkle single-key`
         if witness_check.storage_slots:
             for address, storage_slot, value in witness_check.storage_slots:
-                storage_tree_key = self.get_verkle_single_key(address, storage_slot)
+                storage_tree_key = self.get_verkle_single_key(
+                    address, ZeroPaddedHexNumber(storage_slot)
+                )
                 witness_check_key_values[VerkleHash(storage_tree_key)] = value
 
         # Format code chunks using `evm verkle code-chunk-key`
         if witness_check.code_chunks:
             for address, code_chunk, value in witness_check.code_chunks:
-                code_chunk_tree_key = self.get_verkle_code_chunk_key(address, code_chunk)
+                code_chunk_tree_key = self.get_verkle_code_chunk_key(
+                    address, ZeroPaddedHexNumber(code_chunk)
+                )
                 witness_check_key_values[VerkleHash(code_chunk_tree_key)] = value
 
         return witness_check_key_values
diff --git a/src/evm_transition_tool/transition_tool.py b/src/evm_transition_tool/transition_tool.py
index d00561e5d1..f8f0321d49 100644
--- a/src/evm_transition_tool/transition_tool.py
+++ b/src/evm_transition_tool/transition_tool.py
@@ -15,7 +15,7 @@
 from re import Pattern
 from typing import Dict, List, Mapping, Optional, Type
 
-from ethereum_test_base_types import Address, Alloc
+from ethereum_test_base_types import Address, Alloc, ZeroPaddedHexNumber
 from ethereum_test_fixtures import FixtureFormats, FixtureVerifier
 from ethereum_test_forks import Fork
 from ethereum_test_types import Environment, Transaction
@@ -594,7 +594,9 @@ def get_verkle_state_root(self, mpt_alloc: Alloc) -> bytes:
             " tool."
         )
 
-    def get_verkle_single_key(self, address: Address, storage_slot: Optional[int] = None) -> str:
+    def get_verkle_single_key(
+        self, address: Address, storage_slot: Optional[ZeroPaddedHexNumber] = None
+    ) -> str:
         """
         Returns the VKT key for an account address or storage slot.
         """
@@ -603,7 +605,7 @@ def get_verkle_single_key(self, address: Address, storage_slot: Optional[int] =
             " tool."
         )
 
-    def get_verkle_code_chunk_key(self, address: Address, code_chunk: int) -> str:
+    def get_verkle_code_chunk_key(self, address: Address, code_chunk: ZeroPaddedHexNumber) -> str:
         """
         Returns the VKT key of a code chunk for an account address.
         """
diff --git a/tests/verkle/eip7709_blockhash_witness/test_blockhash_instruction.py b/tests/verkle/eip7709_blockhash_witness/test_blockhash_instruction.py
index 7287d0a100..d837b1eb0c 100644
--- a/tests/verkle/eip7709_blockhash_witness/test_blockhash_instruction.py
+++ b/tests/verkle/eip7709_blockhash_witness/test_blockhash_instruction.py
@@ -93,13 +93,14 @@ def _blockhash(
     )
 
     witness_check = WitnessCheck()
-    witness_check.add_account_full(env.fee_recipient, None)
-    witness_check.add_account_full(TestAddress, pre[TestAddress])
-    # witness_check.add_account_full(TestAddress2, pre[TestAddress2])
-    # if not fail:
-    # storage_slot = block_num_target % HISTORY_STORAGE_ADDRESS
-    # value = None  # TODO(verkle): TODO.
-    # witness_check.add_storage_slot(blockhash_system_contract_address, storage_slot, value)
+    for address in [env.fee_recipient, TestAddress, TestAddress2]:
+        witness_check.add_account_full(
+            address, None if address == env.fee_recipient else pre[address]
+        )
+    if not fail:
+        storage_slot = block_num_target % HISTORY_STORAGE_ADDRESS
+        value = None  # TODO: Process the value for Verkle storage slot
+        witness_check.add_storage_slot(blockhash_system_contract_address, storage_slot, value)
 
     blocks = [Block(txs=[tx], witness_check=witness_check)]
     blockchain_test(