diff --git a/storage/storage-daemon/StorageProvider.cpp b/storage/storage-daemon/StorageProvider.cpp
index da4b5042..e1eb55d6 100644
--- a/storage/storage-daemon/StorageProvider.cpp
+++ b/storage/storage-daemon/StorageProvider.cpp
@@ -259,7 +259,7 @@ void StorageProvider::process_transaction(tl_object_ptr<tonlib_api::raw_transact
     td::Ref<vm::Cell> body = r_body.move_as_ok();
     vm::CellSlice cs = vm::load_cell_slice(body);
     if (cs.size() >= 32) {
-      long long op_code = cs.prefetch_long(32);
+      long long op_code = cs.prefetch_ulong(32);
       // const op::offer_storage_contract = 0x107c49ef; -- old versions
       // const op::deploy_storage_contract = 0xe4748df1; -- new versions
       if((op_code == 0x107c49ef) || (op_code == 0xe4748df1)) {