diff --git a/src/util/wallet_tools.py b/src/util/wallet_tools.py
index f416cf33..9033deab 100644
--- a/src/util/wallet_tools.py
+++ b/src/util/wallet_tools.py
@@ -1,4 +1,4 @@
-from typing import List, Optional, Dict
+from typing import List, Optional, Dict, Tuple
 
 from blspy import PrivateKey, AugSchemeMPL, G1Element, G2Element
 
@@ -129,7 +129,7 @@ class WalletTool:
         condition_dic: Dict[ConditionOpcode, List[ConditionVarPair]],
         fee: int = 0,
         secretkey=None,
-    ) -> List[Tuple[Program, CoinSolution]]:
+    ) -> List[CoinSolution]:
         spends = []
         spend_value = coin.amount
         puzzle_hash = coin.puzzle_hash
diff --git a/src/wallet/puzzles/p2_delegated_puzzle_or_hidden_puzzle.py b/src/wallet/puzzles/p2_delegated_puzzle_or_hidden_puzzle.py
index e6c99d60..ce91a5b6 100644
--- a/src/wallet/puzzles/p2_delegated_puzzle_or_hidden_puzzle.py
+++ b/src/wallet/puzzles/p2_delegated_puzzle_or_hidden_puzzle.py
@@ -69,7 +69,9 @@ def puzzle_for_pk(public_key: PublicKeyProgram) -> Program:
     return MOD.curry(public_key)
 
 
-def solution_with_delegated_puzzle(delegated_puzzle: Program, solution: Program) -> Program:
+def solution_with_delegated_puzzle(
+    delegated_puzzle: Program, solution: Program
+) -> Program:
     return Program.to([[], delegated_puzzle, solution])
 
 
diff --git a/src/wallet/wallet.py b/src/wallet/wallet.py
index e389c22e..befd9251 100644
--- a/src/wallet/wallet.py
+++ b/src/wallet/wallet.py
@@ -13,7 +13,10 @@ from src.util.condition_tools import (
 )
 from src.util.ints import uint64, uint32
 from src.wallet.abstract_wallet import AbstractWallet
-from src.wallet.puzzles.p2_delegated_puzzle import puzzle_for_pk, solution_for_conditions
+from src.wallet.puzzles.p2_delegated_puzzle import (
+    puzzle_for_pk,
+    solution_for_conditions,
+)
 from src.wallet.puzzles.puzzle_utils import (
     make_assert_my_coin_id_condition,
     make_assert_time_exceeds_condition,
@@ -273,9 +276,7 @@ class Wallet(AbstractWallet):
     def secret_key_for_public_key(self, public_key: G1Element) -> Optional[PrivateKey]:
         return self._pk2sk.get(bytes(public_key))
 
-    async def sign_transaction(
-        self, coin_solutions: List[CoinSolution]
-    ) -> SpendBundle:
+    async def sign_transaction(self, coin_solutions: List[CoinSolution]) -> SpendBundle:
         signatures = []
 
         for coin_solution in coin_solutions:
@@ -288,7 +289,9 @@ class Wallet(AbstractWallet):
                 coin_solution.solution
             )
             if err or conditions_dict is None:
-                error_msg = f"Sign transaction failed, con:{conditions_dict}, error: {err}"
+                error_msg = (
+                    f"Sign transaction failed, con:{conditions_dict}, error: {err}"
+                )
                 self.log.error(error_msg)
                 raise ValueError(error_msg)
 
@@ -298,8 +301,9 @@ class Wallet(AbstractWallet):
             ):
                 secret_key = self.secret_key_for_public_key(_)
                 if secret_key is None:
-                    self.log.error(f"no secret key for {_}")
-                    return None
+                    e_msg = f"no secret key for {_}"
+                    self.log.error(e_msg)
+                    raise ValueError(e_msg)
                 signature = AugSchemeMPL.sign(secret_key, msg)
                 signatures.append(signature)
 
diff --git a/tests/full_node/test_mempool.py b/tests/full_node/test_mempool.py
index be3b618c..055537f6 100644
--- a/tests/full_node/test_mempool.py
+++ b/tests/full_node/test_mempool.py
@@ -1,6 +1,6 @@
 import asyncio
 from time import time
-from typing import List, Tuple
+from typing import List
 
 import pytest
 
@@ -9,7 +9,6 @@ from src.protocols import full_node_protocol
 from src.types.coin_solution import CoinSolution
 from src.types.condition_var_pair import ConditionVarPair
 from src.types.condition_opcodes import ConditionOpcode
-from src.types.program import Program
 from src.types.spend_bundle import SpendBundle
 from src.util.condition_tools import (
     conditions_for_solution,
@@ -868,25 +867,23 @@ class TestMempool:
         ):
             pass
 
-        unsigned: List[
-            Tuple[Program, CoinSolution]
-        ] = wallet_a.generate_unsigned_transaction(
+        unsigned: List[CoinSolution] = wallet_a.generate_unsigned_transaction(
             1000, receiver_puzzlehash, block.get_coinbase(), {}, 0
         )
         assert len(unsigned) == 1
+        coin_solution = unsigned[0]
 
-        puzzle, solution = unsigned[0]
-        code_ = [puzzle, solution.solution]
-        sexp = Program.to(code_)
-
-        err, con, cost = conditions_for_solution(sexp)
+        err, con, cost = conditions_for_solution(coin_solution.solution)
         assert con is not None
 
+        puzzle, solution = list(coin_solution.solution.as_iter())
         conditions_dict = conditions_by_opcode(con)
-        pkm_pairs = pkm_pairs_for_conditions_dict(conditions_dict, solution.coin.name())
+        pkm_pairs = pkm_pairs_for_conditions_dict(
+            conditions_dict, coin_solution.coin.name()
+        )
         assert len(pkm_pairs) == 1
 
-        assert pkm_pairs[0][1] == solution.solution.first().get_tree_hash()
+        assert pkm_pairs[0][1] == solution.first().get_tree_hash()
 
         spend_bundle = wallet_a.sign_transaction(unsigned)
         assert spend_bundle is not None