List comp help

[Joseph L. Casale]

I have a dict of lists. I need to create a list of 2 tuples, where each tuple is a key from
the dict with one of the keys list items.

my_dict = {
    'key_a': ['val_a', 'val_b'],
    'key_b': ['val_c'],
    'key_c': []
}
[(k, x) for k, v in my_dict.items() for x in v]

This works, but I need to test for an empty v like the last key, and create one tuple ('key_c', None).
Anyone know the trick to reorganize this to accept the test for an empty v and add the else?

Thanks!
jlc