diff --git a/binding.cc b/binding.cc
index 1899b3a9..67ac9a81 100644
--- a/binding.cc
+++ b/binding.cc
@@ -1077,7 +1077,7 @@ struct ApproximateSizeWorker final : public PriorityWorker {
   void HandleOKCallback () override {
     napi_value argv[2];
     napi_get_null(env_, &argv[0]);
-    napi_create_uint32(env_, (uint32_t)size_, &argv[1]);
+    napi_create_int64(env_, (int64_t)size_, &argv[1]);
     napi_value callback;
     napi_get_reference_value(env_, callbackRef_, &callback);
     CallFunction(env_, callback, 2, argv);