(Harlowe) Performing math with random variables

(click: "crumbs")[''You collect some crumbs!''(set: $Cdrop to (random: 1,4))(set: $Crumbs to "$Crumbs + $Cdrop")]

As you can see, I am trying to make a random drop system that adds to the overall displayed variable. My issue is that it runs the addition function infinitely. I tried setting it to a single number instead of random, but i had the same issue. $Crumbs is set to 0, so I am not sure what I am doing wrong.