The invention relates to a method and an X-ray detector (100) for detecting incident X-ray photons (X). The X-ray detector (100) comprises at least one sensor unit (105) in which X-ray photons (X) are converted into sensor signals (s) and at least one flux sensor (104) for generating a flux signal (f) related to the flux of photons (X). The sensor signals (s) are corrected based on the flux signal (f). In a preferred embodiment, the sensor signals (s) represent a spectrally resolved pulse counting. The flux sensor (104) may be integrated into an ASIC (103) that is coupled to the sensor unit (105).