diff --git a/NineChronicles.Headless/GraphTypes/TransactionHeadlessQuery.cs b/NineChronicles.Headless/GraphTypes/TransactionHeadlessQuery.cs
index f3aeb2a4b..e8ea6a5b5 100644
--- a/NineChronicles.Headless/GraphTypes/TransactionHeadlessQuery.cs
+++ b/NineChronicles.Headless/GraphTypes/TransactionHeadlessQuery.cs
@@ -199,7 +199,7 @@ public TransactionHeadlessQuery(StandaloneContext standaloneContext)
             Field<NonNullGraphType<ListGraphType<TxResultType>>>(
                 name: "transactionResults",
                 arguments: new QueryArguments(
-                    new QueryArgument<NonNullGraphType<ListGraphType<TxIdType>>>
+                    new QueryArgument<NonNullGraphType<ListGraphType<NonNullGraphType<TxIdType>>>>
                     {
                         Name = "txIds",
                         Description = "transaction ids."