An editorial in empirical software engineering suggested that open-source software projects offer a great deal of data that can be used for experimentation. These data include artifacts such as source code and defect reports. In this paper we show that sources of open-source maintenance data, such as defect-tracking systems, change logs, and source code, cannot, in general, be used for measuring maintainability. We further show that approaches such as using defect distributions and the average lag time to fix a defect can be equally unusable. We conclude that, despite the plethora of open-source maintenance data, it is extremely hard to find data for determining the maintainability of open-source software.