diff --git a/lib/galaxy/webapps/galaxy/api/group_users.py b/lib/galaxy/webapps/galaxy/api/group_users.py
index f33499263aa..b1fb16b3235 100644
--- a/lib/galaxy/webapps/galaxy/api/group_users.py
+++ b/lib/galaxy/webapps/galaxy/api/group_users.py
@@ -3,7 +3,9 @@ API operations on Group objects.
 """
 import logging
 
+from galaxy.managers.context import ProvidesAppContext
 from galaxy.managers.group_users import GroupUsersManager
+from galaxy.schema.fields import EncodedDatabaseIdField
 from galaxy.web import (
     expose_api,
     require_admin,
@@ -21,7 +23,7 @@ class GroupUsersAPIController(BaseAPIController):
 
     @require_admin
     @expose_api
-    def index(self, trans, group_id, **kwd):
+    def index(self, trans: ProvidesAppContext, group_id: EncodedDatabaseIdField, **kwd):
         """
         GET /api/groups/{encoded_group_id}/users
         Displays a collection (list) of groups.
@@ -30,7 +32,7 @@ class GroupUsersAPIController(BaseAPIController):
 
     @require_admin
     @expose_api
-    def show(self, trans, id, group_id, **kwd):
+    def show(self, trans: ProvidesAppContext, id: EncodedDatabaseIdField, group_id: EncodedDatabaseIdField, **kwd):
         """
         GET /api/groups/{encoded_group_id}/users/{encoded_user_id}
         Displays information about a group user.
@@ -39,7 +41,7 @@ class GroupUsersAPIController(BaseAPIController):
 
     @require_admin
     @expose_api
-    def update(self, trans, id, group_id, **kwd):
+    def update(self, trans: ProvidesAppContext, id: EncodedDatabaseIdField, group_id: EncodedDatabaseIdField, **kwd):
         """
         PUT /api/groups/{encoded_group_id}/users/{encoded_user_id}
         Adds a user to a group
@@ -48,7 +50,7 @@ class GroupUsersAPIController(BaseAPIController):
 
     @require_admin
     @expose_api
-    def delete(self, trans, id, group_id, **kwd):
+    def delete(self, trans: ProvidesAppContext, id: EncodedDatabaseIdField, group_id: EncodedDatabaseIdField, **kwd):
         """
         DELETE /api/groups/{encoded_group_id}/users/{encoded_user_id}
         Removes a user from a group