Matplotlib.mlab Objects cannot be broadcast to a single shape

Question

My code:

(x, y, t) = mlab.psd(
    d,
    Fs=1.0 / h['xdelta'],
    NFFT=512)
psd = 20 * np.log10(y)
plt.plot(x, y, t)
plt.show()

I just get a the following error upon execution:

ValueError: shape mismatch: objects cannot be broadcast to a single shape.

I feel like this is something simple, but I can't seem to get it to work. How would I go about fixing this?