diff --git a/b2sdk/session.py b/b2sdk/session.py
index 09fc23e17..95bb790a0 100644
--- a/b2sdk/session.py
+++ b/b2sdk/session.py
@@ -508,9 +508,7 @@ def _add_app_key_info_to_unauthorized(self, unauthorized):
             key_messages.append('with no restrictions')
 
         # Make a new message
-        new_message = unauthorized.message
-        if new_message == '':
-            new_message = 'unauthorized'
+        new_message = unauthorized.message or 'unauthorized'
         new_message += ' for application key ' + ', '.join(key_messages)
 
         return Unauthorized(new_message, unauthorized.code)