The transition from school-level mathematics to the more abstract and formal structures in universities poses challenges for many first-year physics students. To address this gap, most physics faculties offer a mathematics pre-course. Here, we report about a pre-posttest study investigating the impact of a pre-course on N = 56 first-year physics students at the Leipzig University. The according tests were conducted in October 2022, which were correlated to the subsequent first and second-semester exam results. Thus, the research focused on measuring the knowledge gain and changes in mathematical abilities before and after the pre-course as well as the resulting medium-term effects. The results show a significant improvement in the math skills of the participants in the pre-course, especially among participants with intermediate prior knowledge. Additionally, the study reveals a correlation between the level of school mathematics instruction and learning success in the pre-course. Medium-term effects revealed that pre-course participants displayed higher pass rates and better grades, particularly in modules directly influenced by pre-course contents. This research underlines the effectiveness of the pre-course in mathematics in improving and reactivating the mathematical skills of first-year physics students.