diff --git a/lib/nodejs/test/int64.test.js b/lib/nodejs/test/int64.test.js
index 106e446..27ad28c 100644
--- a/lib/nodejs/test/int64.test.js
+++ b/lib/nodejs/test/int64.test.js
@@ -18,6 +18,7 @@
  */
 
 const Int64 = require("node-int64");
+const JSONInt64 = require("json-int64");
 const i64types = require("./gen-nodejs-es6/Int64Test_types.js");
 const test = require("tape");
 
@@ -72,6 +73,16 @@
     for (let i = 0; i < EXPECTED_INT64_LIST.length; ++i) {
       assert.ok(EXPECTED_INT64_LIST[i].equals(i64types.INT64_LIST[i]));
     }
+
+    for (let i = 0; i < EXPECTED_INT64_LIST.length; ++i) {
+      const int64Object = EXPECTED_INT64_LIST[i];
+      assert.ok(
+        i64types.INT64_2_INT64_MAP[
+          JSONInt64.toDecimalString(int64Object)
+        ].equals(int64Object)
+      );
+    }
+
     assert.end();
   }
 };