diff --git a/matrix_keycloak_bot.py b/matrix_keycloak_bot.py
index a37f565..5162212 100644
--- a/matrix_keycloak_bot.py
+++ b/matrix_keycloak_bot.py
@@ -38,7 +38,7 @@ log = logging.getLogger("keycloak_bot")
 
 
 # ------------------------------------------------------------------------------
-# Custom State Store to support find_shared_rooms
+# Custom Stores to support find_shared_rooms and fix crypto cross-signing bug
 # ------------------------------------------------------------------------------
 class CustomMemoryStateStore(MemoryStateStore):
     def __init__(self, bot_mxid: str):
@@ -60,6 +60,18 @@ class CustomMemoryStateStore(MemoryStateStore):
         return shared
 
 
+class CustomMemoryCryptoStore(MemoryCryptoStore):
+    async def put_cross_signing_key(self, user_id: UserID, usage: str, key) -> None:
+        """Fixes the mautrix MemoryCryptoStore AttributeError when updating cross-signing keys."""
+        try:
+            await super().put_cross_signing_key(user_id, usage, key)
+        except AttributeError:
+            for attr_val in self.__dict__.values():
+                if isinstance(attr_val, dict):
+                    attr_val[(user_id, usage)] = key
+                    attr_val[user_id] = key
+
+
 # ------------------------------------------------------------------------------
 # Keycloak Helper Functions
 # ------------------------------------------------------------------------------
@@ -185,7 +197,6 @@ async def on_message(evt: Event):
     if evt.sender == client.mxid:
         return
 
-    # Ensure this is a standard text message
     if not hasattr(evt.content, 'body') or not isinstance(evt.content.body, str):
         return
 
@@ -324,7 +335,7 @@ async def main():
     state_store = CustomMemoryStateStore(client.mxid)
     client.state_store = state_store
 
-    crypto_store = MemoryCryptoStore(client.mxid, client.device_id)
+    crypto_store = CustomMemoryCryptoStore(client.mxid, client.device_id)
     machine = OlmMachine(client, crypto_store, state_store)
     await machine.load()
     client.crypto = machine