Estimation of depth to the top of magnetic sources from magnetic anomaly data using various techniques is in common use by geophysicists. Many of the simple models used for this purpose assume that the base of the magnetic body is at infinity. Recent publications have shown that this ‘infinite depth’ assumption causes underestimation of the depth to the top of sources, especially in areas where the bottom of the magnetic layer is shallow, as would occur in high heat-flow regions. This error has been demonstrated in both model studies and using real data with seismic or well control. Local wavenumber is one method of depth estimation based on the spectral content of single anomalies. Here we present a modification to the local wavenumber approach to estimate depth to magnetic sources in areas of shallow Curie temperature and apply it to an example from the central Red Sea where the Curie isotherm and Moho are shallow.