Kerberos with i3-dmenu-desktop

I use Kerberos authentication in Thunderbird, Firefox and for ssh and it works just fine if I use the programs from the shell. But when I use i3-dmenu-desktop to start Thunderbird and Firefox, the Kerberos ticket is not "attached". I use kinit with a cache file, which is exported in my .bashrc (KRB5CCNAME). I do not really know how dmenu works. Is it normal that it does not "inherit" environment variables?