QTableView hangs when number of rows large (>71582788)

When I subclass QAbstractTableModel and embed it within a QTableView, the application hangs when the model's rowCount() result exceeds 71582788. Inserting print statements within the code reveals that, above this limit, Qt starts calling headerData() on every row in the model (which takes forever). I have reproduced this with 2 versions of Qt4, using the PyQt4 and PySide bindings.