  The Gibbons-Maeda-Garfinkle-Horowitz-Strominger (GMGHS) black hole is an
influential solution of the low energy heterotic string theory. As it is well
known, it presents a singular extremal limit. We construct a regular extension
of the GMGHS extremal black hole in a model with $\mathcal{O}(\alpha')$
corrections in the action, by solving the fully non-linear equations of motion.
The de-singularization is supported by the $\mathcal{O}(\alpha')$-terms. The
regularised extremal GMGHS BHs are asymptotically flat, possess a regular
(non-zero size) horizon of spherical topology, with an $AdS_2\times S^2$ near
horizon geometry, and their entropy is proportional to the electric charge. The
near horizon solution is obtained analytically and some illustrative bulk
solutions are constructed numerically.
