how are passwords encoded in pg_shadow How are passwords encoded in column passwd of pg_shadow?

Doing a:

select passwd from pg_shadow;


I see values like the following:

 md52c92c858aa1fa12144f1dcbd4ca9c3a0


... which, doesn't seem to be what I know my password's MD5 hash to be (stripping the leading "md5" obviously). Are the hashes also salted?
It actually suffixes the password with the username and then MD5 hash is made out of that, and that hash is then prefixed with 'md5'