New game icon not working under Linux

With 1.6.1, I noticed on my roommate's Windows PC that the launcher icon has taken the original grass block icon, and the game window now uses a crafting bench icon. With Linux, this has not been reflected.

The normal workaround is to use a .desktop file and set an icon to a process using its WM_CLASS variable, which is what I've done until the 1.6.1 launcher, but the game window that is created with the new launcher does not seem to have such a property, so it seems to be stuck with the ugly, default "?" icon in my environment.

The new crafting bench is available in the .minecraft/assets/icons directory as intended, though I don't know of a way to actually bind it to the process.

The icon for the launcher itself is fine, just not the game.