Protecting the Martian environment from contamination with terrestrial microbes is generally seen as essential to the scientific exploration of Mars, especially when it comes to the search for indigenous life. However, while companies and space agencies aim at getting to Mars within ambitious timelines, the state-of-the-art planetary protection measures are only applicable to uncrewed spacecraft. With this paper, we attempt to reconcile these two conflicting goals: the human exploration of Mars and its protection from biological contamination. In our view, the one nominal mission activity that is most prone to introducing terrestrial microbes into the Martian environment is when humans leave their habitat to explore the Martian surface, if one were to use state-of-the-art airlocks. We therefore propose to adapt airlocks specifically to the goals of planetary protection. We suggest a concrete concept for such an adapted airlock, believing that only practical and implementable solutions will be followed by human explorers in the long run.