diff --git a/jira/resources.py b/jira/resources.py
index 6464dd449..f4c94f7a8 100644
--- a/jira/resources.py
+++ b/jira/resources.py
@@ -42,6 +42,7 @@
     "Customer",
     "ServiceDesk",
     "RequestType",
+    "resource_class_map",
 )
 
 logging.getLogger("jira").addHandler(logging.NullHandler())
@@ -799,7 +800,7 @@ def add_user(self, users=None, groups=None):
         if groups is not None and isinstance(groups, str):
             groups = (groups,)
 
-        data = {"user": users}
+        data = {"user": users, "group": groups}
         self._session.post(self.self, data=json.dumps(data))