Decimal point handling in membership types

Using CiviCRM with German localization, I set the decimal point to be a comma (,) and the thousand separator to be a point (.). Then I set up membership type with a minimum fee of 20,00 which is saved.

On the page that lists all memberships, the fee shows up as "20.00", editing the membership entry fills the field with "20,00".

This difference in formatting the amount leads to a real problem when I want to renew an expired membership and add a payment within that step. The field for the payed amount is filled with "20.00" and produces an "invalid amount" validation error, so that I have to manually correct the field's value to be "20,00" which then is accepted.