1 files changed, 8 insertions, 1 deletions
diff --git a/synapse/rest/client/v2_alpha/account.py b/synapse/rest/client/v2_alpha/account.py
index 085561d3e9..fb5ad2906e 100644
--- a/synapse/rest/client/v2_alpha/account.py
+++ b/synapse/rest/client/v2_alpha/account.py
@@ -884,7 +884,14 @@ class WhoamiRestServlet(RestServlet):
     async def on_GET(self, request):
         requester = await self.auth.get_user_by_req(request)
 
-        return 200, {"user_id": requester.user.to_string()}
+        response = {"user_id": requester.user.to_string()}
+
+        # Appservices and similar accounts do not have device IDs
+        # that we can report on, so exclude them for compliance.
+        if requester.device_id is not None:
+            response["device_id"] = requester.device_id
+
+        return 200, response
 
 
 def register_servlets(hs, http_server):