diff --git a/bumble/keys.py b/bumble/keys.py
index 198d5c49..753575e2 100644
--- a/bumble/keys.py
+++ b/bumble/keys.py
@@ -22,10 +22,11 @@
 # -----------------------------------------------------------------------------
 from __future__ import annotations
 import asyncio
+import dataclasses
 import logging
 import os
 import json
-from typing import TYPE_CHECKING, Dict, List, Optional, Tuple
+from typing import TYPE_CHECKING, Dict, List, Optional, Tuple, Any
 
 from .colors import color
 from .hci import Address
@@ -41,16 +42,17 @@
 
 
 # -----------------------------------------------------------------------------
+@dataclasses.dataclass
 class PairingKeys:
+    @dataclasses.dataclass
     class Key:
-        def __init__(self, value, authenticated=False, ediv=None, rand=None):
-            self.value = value
-            self.authenticated = authenticated
-            self.ediv = ediv
-            self.rand = rand
+        value: bytes
+        authenticated: bool = False
+        ediv: Optional[int] = None
+        rand: Optional[bytes] = None
 
         @classmethod
-        def from_dict(cls, key_dict):
+        def from_dict(cls, key_dict: Dict[str, Any]) -> PairingKeys.Key:
             value = bytes.fromhex(key_dict['value'])
             authenticated = key_dict.get('authenticated', False)
             ediv = key_dict.get('ediv')
@@ -58,9 +60,9 @@ def from_dict(cls, key_dict):
             if rand is not None:
                 rand = bytes.fromhex(rand)
 
-            return cls(value, authenticated, ediv, rand)
+            return cls(value=value, authenticated=authenticated, ediv=ediv, rand=rand)
 
-        def to_dict(self):
+        def to_dict(self) -> Dict[str, Any]:
             key_dict = {'value': self.value.hex(), 'authenticated': self.authenticated}
             if self.ediv is not None:
                 key_dict['ediv'] = self.ediv
@@ -69,17 +71,18 @@ def to_dict(self):
 
             return key_dict
 
-    def __init__(self):
-        self.address_type = None
-        self.ltk = None
-        self.ltk_central = None
-        self.ltk_peripheral = None
-        self.irk = None
-        self.csrk = None
-        self.link_key = None  # Classic
+    address_type: Optional[int] = None
+    ltk: Optional[PairingKeys.Key] = None
+    ltk_central: Optional[PairingKeys.Key] = None
+    ltk_peripheral: Optional[PairingKeys.Key] = None
+    irk: Optional[PairingKeys.Key] = None
+    csrk: Optional[PairingKeys.Key] = None
+    link_key: Optional[PairingKeys.Key] = None  # Classic
 
     @staticmethod
-    def key_from_dict(keys_dict, key_name):
+    def key_from_dict(
+        keys_dict: Dict[str, Any], key_name: str
+    ) -> Optional[PairingKeys.Key]:
         key_dict = keys_dict.get(key_name)
         if key_dict is None:
             return None
@@ -87,7 +90,7 @@ def key_from_dict(keys_dict, key_name):
         return PairingKeys.Key.from_dict(key_dict)
 
     @staticmethod
-    def from_dict(keys_dict):
+    def from_dict(keys_dict: Dict[str, Any]) -> PairingKeys:
         keys = PairingKeys()
 
         keys.address_type = keys_dict.get('address_type')
@@ -100,8 +103,8 @@ def from_dict(keys_dict):
 
         return keys
 
-    def to_dict(self):
-        keys = {}
+    def to_dict(self) -> Dict[str, Any]:
+        keys: Dict[str, Any] = {}
 
         if self.address_type is not None:
             keys['address_type'] = self.address_type
@@ -126,12 +129,12 @@ def to_dict(self):
 
         return keys
 
-    def print(self, prefix=''):
+    def print(self, prefix: str = '') -> None:
         keys_dict = self.to_dict()
-        for (container_property, value) in keys_dict.items():
+        for container_property, value in keys_dict.items():
             if isinstance(value, dict):
                 print(f'{prefix}{color(container_property, "cyan")}:')
-                for (key_property, key_value) in value.items():
+                for key_property, key_value in value.items():
                     print(f'{prefix}  {color(key_property, "green")}: {key_value}')
             else:
                 print(f'{prefix}{color(container_property, "cyan")}: {value}')
@@ -139,7 +142,7 @@ def print(self, prefix=''):
 
 # -----------------------------------------------------------------------------
 class KeyStore:
-    async def delete(self, name: str):
+    async def delete(self, name: str) -> None:
         pass
 
     async def update(self, name: str, keys: PairingKeys) -> None:
@@ -158,7 +161,7 @@ async def delete_all(self) -> None:
     async def get_resolving_keys(self):
         all_keys = await self.get_all()
         resolving_keys = []
-        for (name, keys) in all_keys:
+        for name, keys in all_keys:
             if keys.irk is not None:
                 if keys.address_type is None:
                     address_type = Address.RANDOM_DEVICE_ADDRESS
@@ -168,10 +171,10 @@ async def get_resolving_keys(self):
 
         return resolving_keys
 
-    async def print(self, prefix=''):
+    async def print(self, prefix: str = '') -> None:
         entries = await self.get_all()
         separator = ''
-        for (name, keys) in entries:
+        for name, keys in entries:
             print(separator + prefix + color(name, 'yellow'))
             keys.print(prefix=prefix + '  ')
             separator = '\n'
@@ -229,7 +232,9 @@ class without a namespace. With the default namespace, reading from a file will
     DEFAULT_NAMESPACE = '__DEFAULT__'
     DEFAULT_BASE_NAME = "keys"
 
-    def __init__(self, namespace, filename=None):
+    def __init__(
+        self, namespace: Optional[str], filename: Optional[str] = None
+    ) -> None:
         self.namespace = namespace if namespace is not None else self.DEFAULT_NAMESPACE
 
         if filename is None:
diff --git a/bumble/smp.py b/bumble/smp.py
index f8879c6a..4e7dd0b2 100644
--- a/bumble/smp.py
+++ b/bumble/smp.py
@@ -1348,6 +1348,9 @@ async def on_pairing(self) -> None:
         if self.sc or self.connection.transport == BT_BR_EDR_TRANSPORT:
             keys.ltk = PairingKeys.Key(value=self.ltk, authenticated=authenticated)
         else:
+            if not self.peer_ltk:
+                raise RuntimeError('Peer LTK missing in LE legacy pairing')
+
             our_ltk_key = PairingKeys.Key(
                 value=self.ltk,
                 authenticated=authenticated,