diff --git a/composer.json b/composer.json
index e6de81d..1b03b00 100644
--- a/composer.json
+++ b/composer.json
@@ -13,7 +13,7 @@
   "license": "GPLv2",
   "require": {
     "php": ">=5.3.0",
-    "voku/portable-utf8": "~2.1"
+    "voku/portable-utf8": "~3.0"
   },
   "require-dev": {
     "phpunit/phpunit": "~4.0"