Assigning a random number to individual array elements that meet a certain criteria

I need to find all the elements in an array that are >0 and then replace each one with a random number between 0 and 5 in Python 3.

I have made an array (called L) of 20 elements that each equal 0 or 1, but am struggling to replace elements individually.

I do not want

speed = np.random.randint(0,5) 
L[L > 0] = speed

as this changed all the elements >0 to the same random number.

Any ideas?