diff --git a/package.json b/package.json
index 97b7abf..b850a71 100644
--- a/package.json
+++ b/package.json
@@ -49,6 +49,7 @@
     "eslint-plugin-prettier": "^3.0.0",
     "istanbul": "^0.4.5",
     "jsdoc": "^3.5.5",
+    "json-int64": "^1.0.0",
     "prettier": "^1.14.3",
     "tape": "^4.9.0",
     "utf-8-validate": "^4.0.0",