Charge traps effect in the spectrum of EV Lac. (Top panel) The April 2008 WT observed spectrum (in black) of the flare star EV Lac after the source has faded to a count rate below 150 cts s^-1 is compared to the trap-corrected spectrum (in red). The corrections enhance the main spectral peak at 6.7 keV, but no improvement is seen in the definition of the proposed emission feature at 6.4 keV. (Bottom panel) Using the previous, non trap-corrected gain file, the WT observed spectrum of EV Lac during the late decay of the flare (in black) is compared to the spectrum extracted from the columns most affected by radiation damage (in red). Charge traps cause a shift of the X-ray events to lower energies, that in the most damaged columns results in a bump at energies between 6.3 keV and 6.6 keV.