Below is the code around line 900 for ufuncobject.c (http://svn.scipy.org/svn/numpy/trunk/numpy/core/src/ufuncobject.c) There is a decref labeled with ">>>" below that is incorrect. As per the python documentation (http://docs.python.org/api/dictObjects.html): #PyObject* PyDict_GetItem( PyObject *p, PyObject *key) # #Return value: Borrowed reference. #Return the object from dictionary p which has a key key. Return NULL if the key #key is not present, but without setting an exception. PyDict_GetItem returns a borrowed reference. Therefore this code does not own the contents to which the obj pointer points and should not decref on it. Simply removing the Py_DECREF(obj) line gets rid of the segfault. I was wondering if someone could confirm that my interpretation is correct and remove the line. I don't have access to the svn or know how to change it. Most people do not see this problem because it only affects user defined types. --Tom if (userdef > 0) { PyObject *key, *obj; int ret; obj = NULL; key = PyInt_FromLong((long) userdef); if (key == NULL) return -1; obj = PyDict_GetItem(self->userloops, key); Py_DECREF(key); if (obj == NULL) { PyErr_SetString(PyExc_TypeError, "user-defined type used in ufunc" \ " with no registered loops"); return -1; } /* extract the correct function data and argtypes */ ret = _find_matching_userloop(obj, arg_types, scalars, function, data, self->nargs, self->nin);

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Py_DECREF(obj);

return ret; }