 Tight regulation of retro transposins such as endogenous retroviruses, ERVs, is essential for genome and transcriptome integrity. Here, the authors show that the ATPase function of the chromatin remodellus Markad1 facilitates the binding of KAP1 to ERVs and is required for their repression in embryonic stem cells. This article was authored by Parasatis Saks, Dongding, Philip Bergmeier, and others.