diff --git a/alice/onboarding/onboarding_errors.py b/alice/onboarding/onboarding_errors.py
index d3a1d27..4f70728 100644
--- a/alice/onboarding/onboarding_errors.py
+++ b/alice/onboarding/onboarding_errors.py
@@ -9,7 +9,7 @@
 class OnboardingError(Error):
     operation: str
     code: int
-    message: Dict
+    message: Dict[str, str]
 
     def __str__(self):
         return self.__repr__()