MaximaKernel.shutdown() hangs on OS X

I'm using Maxima 5.37.2

Python 3.5.3 | packaged by conda-forge | (default, Feb 10 2017, 07:09:50) 
[GCC 4.2.1 Compatible Apple LLVM 7.3.0 (clang-703.0.31)] on darwin
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>>> from pymbolic.interop.maxima import MaximaKernel
>>> knl = MaximaKernel()
>>> knl.shutdown()
^CTraceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/matt/pymbolic/pymbolic/interop/maxima.py", line 330, in shutdown
    self.child.wait()
  File "/Users/matt/pymbolic/.miniconda3/envs/py3/lib/python3.5/site-packages/pexpect/pty_spawn.py", line 645, in wait
    exitstatus = ptyproc.wait()
  File "/Users/matt/pymbolic/.miniconda3/envs/py3/lib/python3.5/site-packages/ptyprocess/ptyprocess.py", line 649, in wait
    pid, status = os.waitpid(self.pid, 0)
KeyboardInterrupt