  It is argued, that adjusting strong potentials directly to observed hadronic
atom level shifts may lead to significantly different scattering lengths, than
those, predicted by the Deser formula. On the example of the 1s level shift of
kaonic hydrogen it is demonstrated, that the usually adopted Deser values
deduced from the two recent measurements in KEK and by the DEAR Collaboration
$a_D({\rm KEK}) = 0.78 - 0.49i$ fm and $a_D({\rm DEAR}) = 0.47 - 0.3i$ fm
should be replaced by $a_s({\rm KEK})\simeq 0.85 - 0.62i$ fm and $a_s({\rm
DEAR})\simeq 0.49 - 0.35i$ fm, correspondingly.

Nuclear Theory