diff --git a/osm_nbi/admin_topics.py b/osm_nbi/admin_topics.py
index 768820f..b5246cb 100644
--- a/osm_nbi/admin_topics.py
+++ b/osm_nbi/admin_topics.py
@@ -1085,6 +1085,16 @@
                                 http_code=HTTPStatus.BAD_REQUEST,
                             )
 
+            # username change
+            if indata.get("username"):
+                if not session.get("admin_show"):
+                    if not indata.get("system_admin_id"):
+                        if _id != session["user_id"]:
+                            raise EngineException(
+                                "You are not allowed to change other users username",
+                                http_code=HTTPStatus.BAD_REQUEST,
+                            )
+
             # user = self.show(session, _id)   # Already in 'content'
             original_mapping = content["project_role_mappings"]