Since the 2017 German Federal Election, the electoral system has once more been criticized because it allows to significantly exceed the minimum number of mandates. In order to open avenues for electoral reform, the President of the Bundestag initiated an informal working group comprising members from all parliamentary group. As we know little about how electoral reforms are negotiated within parliament, this article examines how negotiations between parliamentary groups take place and which interests are pursued. Based on the approach that explains electoral reforms by actors’ self‑interest and values, the study builds on interviews with four MPs who served as working group members. Since all members are aware of parliamentary groups’ and MPs’ self‑interest when it comes to electoral law issues, they chose to involve the Federal Election Official in the negotiations. While self‑interest explains the parliamentary groups’ general electoral system preference, values impact the preferred nuanced design.