Students' motivational characteristics, e.g., subject-related interest, are considered important predictors for successful learning processes. However, few empirical studies provide evidence for the assumed chain of effects between high interest and high achievement in mathematics. One reason for this result might be that the applied measures of learners' interest in mathematics are not well aligned with the characteristics of the learning content in the respective educational settings. At the transition from school to university, the character of mathematics shifts from a strongly application oriented school subject to a scientific discipline. When students are asked to rate their interest concerning mathematics learning in general, it is not clear which character of mathematics they refer to (in their ratings). To provide a more differentiated picture of learners' interest, we developed questionnaires that survey students' interest concerning the different characters of mathematics explicitly. With a sample of 323 students from academic mathematics programs, we analysed the quality of the developed scales and whether it is possible to differentiate interest facets according to the different characters of mathematics. In this contribution, we present the development of the instruments. The results of exploratory factor analyses and correlation analyses provide support for the quality of the developed instruments. Our results indicate that indeed the character of mathematics addressed in the questionnaire strongly influences students' self-reports. Finally, we study how the differentiated interest constructs are related to general ratings of interest in mathematics.