diff --git a/package.json b/package.json
index 4ab56f6..498944b 100644
--- a/package.json
+++ b/package.json
@@ -26,7 +26,7 @@
     "url": "https://github.com/aureooms/js-grammar/issues"
   },
   "dependencies": {
-    "@aureooms/js-itertools": "^3.4.0"
+    "@aureooms/js-itertools": "^4.0.0"
   },
   "devDependencies": {
     "@aureooms/js-compare": "1.4.5",