Driver door shuts with a thud as if it's going to fall apart

[X5only]

My 2005 4.4 driver's door shuts with such a thud as if it's going to fall apart. It sounds like there're loose parts inside, but everything works fine. It sounds like a cheap car. The other doors sound like a bimmer door, with a nice soft thump sound.

Any ideas on a fix? Sound deadening insulation? Seals need to be replaced? They look fine though.

Thanks for any pointers.