diff --git a/lib/js/test/test-int64.js b/lib/js/test/test-int64.js
index 4df87e1..cf7e828 100644
--- a/lib/js/test/test-int64.js
+++ b/lib/js/test/test-int64.js
@@ -86,6 +86,12 @@
     for (let i = 0; i < EXPECTED_INT64_LIST.length; ++i) {
       assert.ok(EXPECTED_INT64_LIST[i].equals(Int64Test.INT64_LIST[i]));
     }
+
+    for (let i = 0; i < EXPECTED_INT64_LIST.length; ++i){
+      let int64Object = EXPECTED_INT64_LIST[i];
+      assert.ok(Int64Test.INT64_2_INT64_MAP[JSONInt64.toDecimalString(int64Object)].equals(int64Object));
+    }
+
     console.log('Int64 test -- ends');
   });