diff --git a/bdledger/api/query_service.proto b/bdledger/api/query_service.proto
index 3474d41..0a5736f 100644
--- a/bdledger/api/query_service.proto
+++ b/bdledger/api/query_service.proto
@@ -35,7 +35,7 @@ message BlockFilter {
 message BlocksRequest {
     string ledger = 1;
     repeated BlockFilter filters = 2;
-    required int64 start_timestamp = 3;
+    int64 start_timestamp = 3; // required
     int64 end_timestamp = 4;
 }
 message GetBlocksResponse {
@@ -50,7 +50,7 @@ message CountBlocksResponse {
 message TransactionsRequest {
     string ledger = 1;
     repeated TransactionFilter filters = 2;
-    required int64 start_timestamp = 3;
+    int64 start_timestamp = 3; // required
     int64 end_timestamp = 4;
 }
 message GetTransactionsResponse {