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

[zapamix]

composer require mglaman/drupal-check --dev

Problem 1
- Conclusion: don't install mglaman/drupal-check 1.1.1
- mglaman/drupal-check 1.1.0 conflicts with composer/package-versions-deprecated[1.8.0].
- mglaman/drupal-check 1.1.0 conflicts with composer/package-versions-deprecated[dev-master].
- mglaman/drupal-check 1.1.0 conflicts with composer/package-versions-deprecated[1.x-dev].
- mglaman/drupal-check 1.1.0 conflicts with ocramius/package-versions[1.5.1].
- mglaman/drupal-check 1.1.0 conflicts with ocramius/package-versions[1.5.1].
- mglaman/drupal-check 1.1.0 conflicts with ocramius/package-versions[1.5.1].
- Installation request for mglaman/drupal-check ^1.1 -> satisfiable by mglaman/drupal-check[1.1.0, 1.1.1].
- Installation request for ocramius/package-versions (locked at 1.5.1) -> satisfiable by composer/package-versions-deprecated[1.8.0, dev-master, 1.x-dev], ocramius/package-versions[1.5.1].

[mglaman]

Before this was enough, I guess not

    "conflict": {
        "ocramius/package-versions": ">=1.5"
    },