Significance Repression of the large number of transposable elements in eukaryotic genomes is essential for genome stability. The Piwi-interacting RNA and short interfering RNA pathways are critical for repressing transposable elements in germlines, but the repression of transposable elements in somatic tissues involves other components. While the mammalian Hinfp has been shown to regulate Histone4 and cell-cycle progression, our manuscript provides evidence that a function of the Drosophila Hinfp is to maintain Histone1 expression to repress most transposable elements in somatic genomes. This Hinfp–Histone1 axis provides a venue to study maintenance of genome stability and progression of pathological outcomes.