diff --git a/starknet_devnet/contracts.py b/starknet_devnet/contracts.py
index 85fece555..8b6621481 100644
--- a/starknet_devnet/contracts.py
+++ b/starknet_devnet/contracts.py
@@ -2,6 +2,7 @@
 Class for storing and handling contracts
 """
 
+from typing import Dict
 from .origin import Origin
 from .util import (
     StarknetDevnetException,
@@ -16,21 +17,21 @@ class DevnetContracts:
 
     def __init__(self, origin: Origin):
         self.origin = origin
-        self.__intstances = {}
+        self.__instances: Dict[int, ContractWrapper] = {}
 
-    def store(self, address: str, contract: ContractWrapper) -> None:
+    def store(self, address: int, contract: ContractWrapper) -> None:
         """
         Store the contract wrapper.
         """
-        self.__intstances[address] = contract
+        self.__instances[address] = contract
 
-    def is_deployed(self, address: str) -> bool:
+    def is_deployed(self, address: int) -> bool:
         """
         Check if the contract is deployed.
         """
-        return address in self.__intstances
+        return address in self.__instances
 
-    def get_by_address(self, address: str) -> ContractWrapper:
+    def get_by_address(self, address: int) -> ContractWrapper:
         """
         Get the contract wrapper by address.
         """
@@ -38,18 +39,18 @@ def get_by_address(self, address: str) -> ContractWrapper:
             message = f"No contract at the provided address ({fixed_length_hex(address)})."
             raise StarknetDevnetException(message=message)
 
-        return self.__intstances[address]
+        return self.__instances[address]
 
-    def get_code(self, address: str) -> str:
+    def get_code(self, address: int) -> str:
         """
         Get the contract code by address.
         """
         if not self.is_deployed(address):
             return self.origin.get_code(address)
 
-        return self.__intstances[address].code
+        return self.__instances[address].code
 
-    def get_full_contract(self, address: str) -> ContractWrapper:
+    def get_full_contract(self, address: int) -> ContractWrapper:
         """
         Get the contract wrapper by address.
         """
diff --git a/starknet_devnet/util.py b/starknet_devnet/util.py
index b3803b23c..b8dc22012 100644
--- a/starknet_devnet/util.py
+++ b/starknet_devnet/util.py
@@ -16,7 +16,7 @@
 DEFAULT_HOST = "127.0.0.1"
 DEFAULT_PORT = 5050
 
-def custom_int(arg: str) -> str:
+def custom_int(arg: str) -> int:
     """
     Converts the argument to an integer.
     Conversion base is 16 if `arg` starts with `0x`, otherwise `10`.