diff --git a/cas_wrapper.py b/cas_wrapper.py
index e5990a4..8cb648b 100644
--- a/cas_wrapper.py
+++ b/cas_wrapper.py
@@ -1,4 +1,5 @@
 import json
+from typing import Dict
 
 from plumbum import local, ProcessExecutionError
 
@@ -48,7 +49,7 @@ class CasWrapper:
     def authenticate(
             self,
             local_path: str,
-            metadata: dict = None,
+            metadata: Dict = None,
     ):
         """
         Wrapper around `cas authenticate`