diff --git a/keyserver/storage/postgres/one_time_keys_table.go b/keyserver/storage/postgres/one_time_keys_table.go
index d8c76b49b9..2117efcae6 100644
--- a/keyserver/storage/postgres/one_time_keys_table.go
+++ b/keyserver/storage/postgres/one_time_keys_table.go
@@ -53,7 +53,9 @@ const selectKeysSQL = "" +
 	"SELECT concat(algorithm, ':', key_id) as algorithmwithid, key_json FROM keyserver_one_time_keys WHERE user_id=$1 AND device_id=$2 AND concat(algorithm, ':', key_id) = ANY($3);"
 
 const selectKeysCountSQL = "" +
-	"SELECT algorithm, COUNT(key_id) FROM keyserver_one_time_keys WHERE user_id=$1 AND device_id=$2 GROUP BY algorithm"
+	"SELECT algorithm, COUNT(key_id) FROM " +
+	" (SELECT algorithm, key_id FROM keyserver_one_time_keys WHERE user_id = $1 AND device_id = $2 LIMIT 100)" +
+	" x GROUP BY algorithm"
 
 const deleteOneTimeKeySQL = "" +
 	"DELETE FROM keyserver_one_time_keys WHERE user_id = $1 AND device_id = $2 AND algorithm = $3 AND key_id = $4"
diff --git a/keyserver/storage/sqlite3/one_time_keys_table.go b/keyserver/storage/sqlite3/one_time_keys_table.go
index d2c0b7b200..7a923d0e52 100644
--- a/keyserver/storage/sqlite3/one_time_keys_table.go
+++ b/keyserver/storage/sqlite3/one_time_keys_table.go
@@ -52,7 +52,9 @@ const selectKeysSQL = "" +
 	"SELECT key_id, algorithm, key_json FROM keyserver_one_time_keys WHERE user_id=$1 AND device_id=$2"
 
 const selectKeysCountSQL = "" +
-	"SELECT algorithm, COUNT(key_id) FROM keyserver_one_time_keys WHERE user_id=$1 AND device_id=$2 GROUP BY algorithm"
+	"SELECT algorithm, COUNT(key_id) FROM " +
+	" (SELECT algorithm, key_id FROM keyserver_one_time_keys WHERE user_id = $1 AND device_id = $2 LIMIT 100)" +
+	" x GROUP BY algorithm"
 
 const deleteOneTimeKeySQL = "" +
 	"DELETE FROM keyserver_one_time_keys WHERE user_id = $1 AND device_id = $2 AND algorithm = $3 AND key_id = $4"
diff --git a/syncapi/sync/requestpool.go b/syncapi/sync/requestpool.go
index 8ab130911a..30c490df05 100644
--- a/syncapi/sync/requestpool.go
+++ b/syncapi/sync/requestpool.go
@@ -248,7 +248,15 @@ func (rp *RequestPool) OnIncomingSyncRequest(req *http.Request, device *userapi.
 		defer userStreamListener.Close()
 
 		giveup := func() util.JSONResponse {
+			syncReq.Log.Debugln("Responding to sync since client gave up or timeout was reached")
 			syncReq.Response.NextBatch = syncReq.Since
+			// We should always try to include OTKs in sync responses, otherwise clients might upload keys
+			// even if that's not required. See also:
+			// https://github.com/matrix-org/synapse/blob/29f06704b8871a44926f7c99e73cf4a978fb8e81/synapse/rest/client/sync.py#L276-L281
+			err = internal.DeviceOTKCounts(syncReq.Context, rp.keyAPI, syncReq.Device.UserID, syncReq.Device.ID, syncReq.Response)
+			if err != nil {
+				syncReq.Log.WithError(err).Error("failed to get OTK counts")
+			}
 			return util.JSONResponse{
 				Code: http.StatusOK,
 				JSON: syncReq.Response,