  We study the corrections to the entropy of Einstein-Maxwell dilaton-axion
black holes beyond semiclassical approximations. We consider the entropy of the
black hole as a state variable and derive these corrections using the exactness
criteria of the first law of thermodynamics. We note that from this general
frame-work the entropy corrections for "simpler" black holes like
Schwarzschild, Reissner-Nordstr\"{o}m and anti-de Sitter-Schwarzschild black
holes follow easily. This procedure gives us the modified area law as well.
