diff --git a/synapse/storage/client_ips.py b/synapse/storage/client_ips.py
index a4e6d9dbe74f5d762972661e477d9563e3fbebfa..8996689744d4931720358c4e1dcf848bdf0df809 100644
--- a/synapse/storage/client_ips.py
+++ b/synapse/storage/client_ips.py
@@ -393,7 +393,7 @@ class ClientIpStore(background_updates.BackgroundUpdateStore):
         """
 
         keyvalues = {"user_id": user_id}
-        if device_id:
+        if device_id is not None:
             keyvalues["device_id"] = device_id
 
         res = yield self._simple_select_list(