Laminar gas-liquid flow through a channel with corrugated bottom, driven by a combination of gravity and pressure drop, is considered. A linear analysis, valid for small-amplitude disturbances but arbitrary wavelength and Re number, leads to Orr-Sommerfeld type equations with nonhomogeneous boundary conditions. The interface amplitude relative to the wall is examined and linearly infinite amplification is computed at specific resonance conditions. With increasing gas velocity,the range of corrugation wavelengths most active in producing strong interaction with the interface expands considerably, and moves to higher values. It is argued that the resonant phenomenon under consideration may influence the interfacial dynamics of gas-liquid flows in small-scale passages.