diff --git a/cashu/core/base.py b/cashu/core/base.py
index d8b3e9f..afc7335 100644
--- a/cashu/core/base.py
+++ b/cashu/core/base.py
@@ -6,13 +6,9 @@ from typing import Any, Dict, List, Optional, TypedDict, Union
 from loguru import logger
 from pydantic import BaseModel
 
-from ..core.crypto import (
-    derive_keys,
-    derive_keys_backwards_compatible_0_11_insecure,
-    derive_keyset_id,
-    derive_pubkeys,
-)
+from ..core.crypto import derive_keys, derive_keyset_id, derive_pubkeys
 from ..core.secp import PrivateKey, PublicKey
+from .legacy import derive_keys_backwards_compatible_insecure_pre_0_12
 
 # ------- PROOFS -------
 
@@ -299,7 +295,7 @@ class MintKeyset:
         ):
             backwards_compatibility_pre_0_12 = True
             # WARNING: Broken key derivation for backwards compatibility with < 0.12
-            self.private_keys = derive_keys_backwards_compatible_0_11_insecure(
+            self.private_keys = derive_keys_backwards_compatible_insecure_pre_0_12(
                 seed, self.derivation_path
             )
         else:
diff --git a/cashu/core/crypto.py b/cashu/core/crypto.py
index 44cd8f5..4f4384c 100644
--- a/cashu/core/crypto.py
+++ b/cashu/core/crypto.py
@@ -31,24 +31,6 @@ def derive_keys(master_key: str, derivation_path: str = ""):
     }
 
 
-def derive_keys_backwards_compatible_0_11_insecure(
-    master_key: str, derivation_path: str = ""
-):
-    """
-    WARNING: Broken key derivation for backwards compatibility with 0.11.
-    """
-    return {
-        2
-        ** i: PrivateKey(
-            hashlib.sha256((master_key + derivation_path + str(i)).encode("utf-8"))
-            .hexdigest()
-            .encode("utf-8")[:32],
-            raw=True,
-        )
-        for i in range(settings.max_order)
-    }
-
-
 def derive_pubkey(master_key: str):
     return PrivateKey(
         hashlib.sha256((master_key).encode("utf-8")).digest()[:32],
diff --git a/cashu/core/legacy.py b/cashu/core/legacy.py
index 7434bdf..75186cc 100644
--- a/cashu/core/legacy.py
+++ b/cashu/core/legacy.py
@@ -1,6 +1,8 @@
 import hashlib
 
-from secp256k1 import PublicKey
+from secp256k1 import PrivateKey, PublicKey
+
+from ..core.settings import settings
 
 
 def hash_to_point_pre_0_3_3(secret_msg):
@@ -13,7 +15,7 @@ def hash_to_point_pre_0_3_3(secret_msg):
     point = None
     msg = secret_msg
     while point is None:
-        _hash = hashlib.sha256(msg).hexdigest().encode("utf-8")
+        _hash = hashlib.sha256(msg).hexdigest().encode("utf-8")  # type: ignore
         try:
             # We construct compressed pub which has x coordinate encoded with even y
             _hash = list(_hash[:33])  # take the 33 bytes and get a list of bytes
@@ -28,4 +30,22 @@ def hash_to_point_pre_0_3_3(secret_msg):
 
 def verify_pre_0_3_3(a, C, secret_msg):
     Y = hash_to_point_pre_0_3_3(secret_msg.encode("utf-8"))
-    return C == Y.mult(a)
+    return C == Y.mult(a)  # type: ignore
+
+
+def derive_keys_backwards_compatible_insecure_pre_0_12(
+    master_key: str, derivation_path: str = ""
+):
+    """
+    WARNING: Broken key derivation for backwards compatibility with 0.11.
+    """
+    return {
+        2
+        ** i: PrivateKey(
+            hashlib.sha256((master_key + derivation_path + str(i)).encode("utf-8"))
+            .hexdigest()
+            .encode("utf-8")[:32],
+            raw=True,
+        )
+        for i in range(settings.max_order)
+    }
diff --git a/cashu/core/secp.py b/cashu/core/secp.py
index 3341643..d0bb0e1 100644
--- a/cashu/core/secp.py
+++ b/cashu/core/secp.py
@@ -21,7 +21,7 @@ class PublicKeyExt(PublicKey):
 
     def __sub__(self, pubkey2):
         if isinstance(pubkey2, PublicKey):
-            return self + (-pubkey2)
+            return self + (-pubkey2)  # type: ignore
         else:
             raise TypeError("Can't add pubkey and %s" % pubkey2.__class__)
 
@@ -34,19 +34,20 @@ class PublicKeyExt(PublicKey):
     def __eq__(self, pubkey2):
         if isinstance(pubkey2, PublicKey):
             seq1 = self.to_data()
-            seq2 = pubkey2.to_data()
+            seq2 = pubkey2.to_data()  # type: ignore
             return seq1 == seq2
         else:
             raise TypeError("Can't compare pubkey and %s" % pubkey2.__class__)
 
     def to_data(self):
+        assert self.public_key
         return [self.public_key.data[i] for i in range(64)]
 
 
 # Horrible monkeypatching
-PublicKey.__add__ = PublicKeyExt.__add__
-PublicKey.__neg__ = PublicKeyExt.__neg__
-PublicKey.__sub__ = PublicKeyExt.__sub__
-PublicKey.mult = PublicKeyExt.mult
-PublicKey.__eq__ = PublicKeyExt.__eq__
-PublicKey.to_data = PublicKeyExt.to_data
+PublicKey.__add__ = PublicKeyExt.__add__  # type: ignore
+PublicKey.__neg__ = PublicKeyExt.__neg__  # type: ignore
+PublicKey.__sub__ = PublicKeyExt.__sub__  # type: ignore
+PublicKey.mult = PublicKeyExt.mult  # type: ignore
+PublicKey.__eq__ = PublicKeyExt.__eq__  # type: ignore
+PublicKey.to_data = PublicKeyExt.to_data  # type: ignore
diff --git a/tests/test_mint.py b/tests/test_mint.py
index 534d2b1..dcc5487 100644
--- a/tests/test_mint.py
+++ b/tests/test_mint.py
@@ -12,6 +12,7 @@ import os
 
 from cashu.core.db import Database
 from cashu.core.settings import settings
+from cashu.lightning.fake import FakeWallet
 from cashu.mint import migrations
 from cashu.mint.ledger import Ledger
 
@@ -46,7 +47,7 @@ async def ledger():
         db=Database("test", "data/mint"),
         seed="TEST_PRIVATE_KEY",
         derivation_path="0/0/0/0",
-        lightning=None,
+        lightning=FakeWallet(),
     )
     await start_mint_init(ledger)
     yield ledger