Teachers often provide more positive feedback to ethnic minority students than to ethnic majority students in order to compensate for potential discrimination. However, even feedback that sounds positive can have unwanted effects on the students, such as reinforcing negative beliefs and reducing motivation. In this experimental pilot study, we investigated whether teachers were more likely to convey such dysfunctional feedback to students from immigrant backgrounds than to students from non-immigrant backgrounds. Teachers (N = 186) read descriptions of classroom situations and indicated the feedback they would provide to the fictive students. The students' names implied either an immigrant background associated with low competence stereotypes or no immigrant background. For the most part, feedback did not differ according to immigrant status. Yet, there were some situation-specific differences: When immigrant students failed despite effort, teachers used a simpler language in their feedback. In one of two scenarios describing students who succeeded easily without effort, teachers were more likely to provide dysfunctional ability feedback, dysfunctional effort feedback, and inflated praise to a student from an immigrant background than to a student from a non-immigrant background. A subsequent expert survey (N = 12) was conducted to evaluate the scenario-based feedback test. In sum, the study contributes to the field by providing first signs that students from immigrant backgrounds might be at risk of receiving not only more positive but actually more dysfunctional feedback. Furthermore, the study presents a practice-oriented, standardized, and economic instrument to assess teachers' dysfunctional feedback, which may be used in future research.