gistfile1.txt

Chriss-MacBook-Pro:laravel ccornutt$ composer require psecio/gatekeeper
Using version ^2.6 for psecio/gatekeeper
./composer.json has been updated
> php artisan clear-compiled
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Installation request for vlucas/phpdotenv == 1.1.1.0 -> satisfiable by vlucas/phpdotenv[v1.1.1].
    - psecio/gatekeeper 2.6 requires vlucas/phpdotenv 1.1.0 -> satisfiable by vlucas/phpdotenv[v1.1.0].
    - psecio/gatekeeper 2.6.1 requires vlucas/phpdotenv 1.1.0 -> satisfiable by vlucas/phpdotenv[v1.1.0].
    - Conclusion: don't install vlucas/phpdotenv v1.1.0
    - Installation request for psecio/gatekeeper ^2.6 -> satisfiable by psecio/gatekeeper[2.6, 2.6.1].


Installation failed, reverting ./composer.json to its original content.

Cannot reproduce. I just issued the following commands and both ran fine:

composer.phar require psecio/gatekeeper
composer.phar require laravel/laravel

Have to tried to update your composer executable?

Can you try them in the reverse order? :)

And there the error is ;)