I wanted to re-offer for discussion a fix for a bug I reported a while back. The code that breaks is this: import numpy cimport numpy def testfunc(): a = numpy.arange(12).reshape([3,4]) cdef numpy.int_t[:,:] a_view = a cdef numpy.int_t[:,:] b = a_view[:,:].T One problem is that when a memoryview slice is decremented, the .memview and .data fields are not set to NULL, and any error that causes a jump to cleanup code will attempt to decref it again. The second problem (I think) is that assignment of a transpose of memoryview slices to a variable is not resulting in an incref on the underlying slice, even though the variable is not a temporary and continues to persist. Here is a patch that solves the problem for me. https://github.com/SyamGadde/cython/commit/5739d8b908f18c4fc9103ef04e39964d6... The part I am least sure about is removing the "if" qualifications on the incref and decref: if self.obj.is_name or self.obj.is_attribute and self.obj.is_memslice_transpose: that was obviously there for a reason, but it causes problems in the above case. If there is a less extreme solution I'd be happy to take it. Thanks, -syam