We consider a thin viscous liquid film flow down an inclined plane with sinusoidal topography. We use the integral boundary layer approach to derive governing equations. By use of Floquet theory, we study linear stability of steady-state flow. For small values of the topography amplitude, perturbation analysis gives an analytical expression for corrections to the growth rate of a normal mode disturbance. This correction is proportional to the second power of the topography amplitude. The topography can both stabilize and destabilize the flow, depending on the corrugation period and the plane inclination angle. We study the topology of neutral curves and the critical Reynolds number dependence on topography parameters. (C) 2019 Elsevier Ltd. All rights reserved.