Keras visualization not working

[trent-b]

When running the following code:

from keras.utils import plot_model
plot_model(model, to_file='model.png')

I receive the following error:
OSError: pydot failed to call GraphViz.Please install GraphViz (https://www.graphviz.org/) and ensure that its executables are in the $PATH.

From what I've read, GraphViz has to be installed with apt-get, not just with pip.