1 files changed, 2 insertions, 1 deletions
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.