When you have multiple modules that use hook_civicrm_validate, only one of the hooks works

Right now I have one huge sprawling drupal module that does most of the customizations for our CiviCRM site. I'm splitting it out into separate modules so things will be more organized.

But I discovered that if two modules both implement hook_civicrm_validate, the hook only counts for the first one. The hook_civicrm_validate hook gets run in both modules, but if the first module validates fine and the second module returns an errors array, those errors get ignored and the form as a whole validates when it shouldn't.

The only work-around right now is to put all of my hook_civicrm_validate code in the same module.