diff --git a/composer.json b/composer.json
index 6cbad58..17ec18c 100644
--- a/composer.json
+++ b/composer.json
@@ -11,7 +11,7 @@
     "hhvm/hsl": "^4.0",
     "hhvm/type-assert": "^4.0",
     "hhvm/hsl-experimental": "^4.58.0rc1",
-    "hhvm/hsl-io": "0.2.0"
+    "hhvm/hsl-io": "^0.2.0"
   },
   "require-dev": {
     "facebook/fbexpect": "^2.6.1",