Cognitive biases distort the process of rational decision-making, including architectural decision-making. So far, no method has been empirically proven to reduce the impact of cognitive biases on architectural decision-making. We conducted an experiment in which 44 master's degree graduate students took part. Divided into 12 teams, they created two designs - before and after a debiasing workshop. We recorded this process and analysed how the participants discussed their decisions. In most cases (10 out of 12 groups), the teams' reasoning improved after the workshop. Thus, we show that debiasing architectural decision-making is an attainable goal and provide a simple debiasing treatment that could easily be used when training software practitioners.