Recent studies documented that the act of writing explanations improves students' learning only to a limited extent, as students attend less frequently to genre-typical features of comprehensibility during writing explanations (i.e., cohesion). In this study, we investigated whether learning by writing explanations can be enhanced when students additionally receive computer-based feedback on the cohesion of their explanations. Sixty-one advanced students studied a hyper-text about photovoltaic panels. Afterwards, they provided a written explanation about the learning content. During writing, students randomly received either individual computer-based feedback in the form of a concept map or not. Our findings indicated that students who received additional concept map feedback outperformed students without such feedback on a transfer test. Mediation analyses revealed that the effect of the concept map feedback on students' transfer was mediated by the level of global cohesion of the provided explanations. Thus, we can conclude that learning by writing explanations can be enhanced by formative computer-based feedback that provides specific information about the quality of students' written explanations.