diff --git a/test/functional/interface_rest.py b/test/functional/interface_rest.py
index 1ba8f60d99..c0679c5ba9 100755
--- a/test/functional/interface_rest.py
+++ b/test/functional/interface_rest.py
@@ -26,6 +26,7 @@ from test_framework.wallet import (
     MiniWallet,
     getnewdestination,
 )
+from typing import Optional
 
 
 INVALID_PARAM = "abc"
@@ -64,7 +65,7 @@ class RESTTest (BitcoinTestFramework):
             body: str = '',
             status: int = 200,
             ret_type: RetType = RetType.JSON,
-            query_params: typing.Dict[str, typing.Any] = None,
+            query_params: Optional[typing.Dict[str, typing.Any]] = None,
             ) -> typing.Union[http.client.HTTPResponse, bytes, str, None]:
         rest_uri = '/rest' + uri
         if req_type in ReqType:
diff --git a/test/functional/test_framework/coverage.py b/test/functional/test_framework/coverage.py
index 4fb4f8bb82..912a945d95 100644
--- a/test/functional/test_framework/coverage.py
+++ b/test/functional/test_framework/coverage.py
@@ -11,6 +11,7 @@ testing.
 import os
 
 from .authproxy import AuthServiceProxy
+from typing import Optional
 
 REFERENCE_FILENAME = 'rpc_interface.txt'
 
@@ -20,7 +21,7 @@ class AuthServiceProxyWrapper():
     An object that wraps AuthServiceProxy to record specific RPC calls.
 
     """
-    def __init__(self, auth_service_proxy_instance: AuthServiceProxy, rpc_url: str, coverage_logfile: str=None):
+    def __init__(self, auth_service_proxy_instance: AuthServiceProxy, rpc_url: str, coverage_logfile: Optional[str]=None):
         """
         Kwargs:
             auth_service_proxy_instance: the instance being wrapped.
diff --git a/test/functional/test_framework/util.py b/test/functional/test_framework/util.py
index e480d63e03..9143397042 100644
--- a/test/functional/test_framework/util.py
+++ b/test/functional/test_framework/util.py
@@ -309,7 +309,7 @@ class PortSeed:
     n = None
 
 
-def get_rpc_proxy(url: str, node_number: int, *, timeout: int=None, coveragedir: str=None) -> coverage.AuthServiceProxyWrapper:
+def get_rpc_proxy(url: str, node_number: int, *, timeout: Optional[int]=None, coveragedir: Optional[str]=None) -> coverage.AuthServiceProxyWrapper:
     """
     Args:
         url: URL of the RPC server to call