After fixing the usage of PyArray_CanCastSafely, now all scipy tests, except one, are succesfull on a 64-bit machine: ====================================================================== ERROR: check_integer (scipy.io.array_import.test_array_import.test_read_array) ---------------------------------------------------------------------- Traceback (most recent call last): File "/usr/local/lib/python2.3/site-packages/scipy/io/tests/test_array_import.py", line 62, in check_integer b = io.read_array(fname,atype=N.Int) File "/usr/local/lib/python2.3/site-packages/scipy/io/array_import.py", line 359, in read_array raise ValueError, "One of the array types is invalid, k=%d" % k ValueError: One of the array types is invalid, k=0 ---------------------------------------------------------------------- Ran 1334 tests in 57.772s FAILED (errors=1) Pearu