Laravel 安装报错

执行命令composer create-project laravel/laravel blog报错:

Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Installation request for laravel/framework v5.0.16 -> satisfiable by laravel/framework[v5.0.16].
    - laravel/framework v5.0.16 requires ext-mcrypt * -> the requested PHP extension mcrypt is missing from your system.

问题是我已经安装了mcrypt。

brew info mcrypt
mcrypt: stable 2.6.8

新手发帖，求指教。