http://bugs.python.org/review/17401/diff/13116/Modules/_io/fileio.c File Modules/_io/fileio.c (right): http://bugs.python.org/review/17401/diff/13116/Modules/_io/fileio.c#newcode1... Modules/_io/fileio.c:1059: self->fd, mode_string(self), self->closefd ? "" : " closefd=False"); So this will work, but its more complex for folk to reason about. http://bugs.python.org/review/17401/diff/13116/Modules/_io/fileio.c#newcode1... Modules/_io/fileio.c:1064: nameobj, mode_string(self), self->closefd ? "" : " closefd=False"); OTOH this code path here may make sense to hide closefd altogether, since closefd cannot be specified with file names (rather than fds) - its always treated as True. http://bugs.python.org/review/17401/