While holding back a struggling elementary school student may seem like it would be a blow to a young child’s confidence, it can actually end up helping him, according to a new working paper published by the National Bureau of Economic Research.

The study shows that students who repeat the third grade show short-term gains in both math and reading. Five years later, these gains are still significant compared to those of peers of the same grade. Compared to students of the same age, the gains fade out over five years.