diff --git a/syncapi/sync/requestpool.go b/syncapi/sync/requestpool.go
index 61f8c46f7..c75787000 100644
--- a/syncapi/sync/requestpool.go
+++ b/syncapi/sync/requestpool.go
@@ -328,7 +328,9 @@ func (rp *RequestPool) appendAccountData(
 	// data keys were set between two message. This isn't a huge issue since the
 	// duplicate data doesn't represent a huge quantity of data, but an optimisation
 	// here would be making sure each data is sent only once to the client.
-	if req.since == nil {
+	// TODO: We used to have req.since == nil here, is there any case where req.since
+	// can actually be nil?
+	if req.since.PDUPosition() == 0 && req.since.EDUPosition() == 0 {
 		// If this is the initial sync, we don't need to check if a data has
 		// already been sent. Instead, we send the whole batch.
 		dataReq := &userapi.QueryAccountDataRequest{