OS X: How to change an alias icon?

I recently did some backup/restores and I noticed that the restored aliases, although fully functional, did not preserve the original icons.

Inspecting the aliases with right click → Get Info shows the correct icon, just that it is not effective in Finder.

Alias Icon.

Now the trick: select the icon, copy, paste, and… the icon is again visible in Finder!

The copy/paste mechanism was probably intended to copy icons from one file to the other, but in this case simply copying the icon onto itself is enough to refresh the Finder look.