This article was initially meant as a review of bugs found in the FreeCAD open-source project but eventually took a bit different direction. It happened because a considerable portion of the warnings had been generated for the third-party libraries employed by the project. Extensive use of third-party libraries in software development is highly beneficial, especially in the open-source software domain. And bugs found in these libraries are no good reason to reject them. But we still should keep in mind that third-party code we use in our projects may contain bugs, so we must be prepared to meet and, if possible, fix them, thus improving the libraries.