diff --git a/composer.json b/composer.json
index 57be51a..423ce35 100644
--- a/composer.json
+++ b/composer.json
@@ -14,7 +14,7 @@
   "require": {
     "hhvm/hsl": "^4.0.1",
     "hhvm/hsl-experimental": "^4.0.2",
-    "facebook/hack-codegen": "^4.2.1",
+    "facebook/hack-codegen": "^4.1.0",
     "facebook/hh-clilib": "^2.0.0",
     "hhvm/hhvm-autoload": "^2.0.4"
   },