•Electrostatic effects degrade the quality of mass spectra for electrically insulating samples in straight-flight-path atom probe microscopes.•A parameter-free ‘systematic energy deficit’ correction was developed to correct for the electrostatic effects.•The ‘systematic energy deficit’ correction significantly improves the quality of CeO2 and SiO2 mass spectra. Improvements in the mass resolution of a mass spectrometer directly correlate to improvements in peak identification and quantification. Here, we describe a post-processing technique developed to increase the quality of mass spectra of strongly insulating samples in laser-pulsed atom probe microscopy. The technique leverages the self-similarity of atom probe mass spectra collected at different times during an experimental run to correct for electrostatic artifacts that present as systematic energy deficits. We demonstrate the method on fused silica (SiO2) and neodymium-doped ceria (CeO2) samples which highlight the improvements that can be made to the mass spectrum of strongly insulating samples.