diff --git a/composer.json b/composer.json
index b24d306..33da8a6 100644
--- a/composer.json
+++ b/composer.json
@@ -16,7 +16,7 @@
   ],
   "require": {
     "phing/phing": "~2.9",
-    "drush/drush": "6.5 - 8.1"
+    "drush/drush": "6.5 - 9.9"
   },
   "autoload": {
     "psr-0": {