Unwinding strings in semi-flatland

We study the dynamics of strings with non-zero winding number around T-duality defects. We deduce that the physics near the core of such non-geometric objects involves winding modes that are not captured by the supergravity approximation, and we argue that such corrections are T-dual to the modes responsible for quantum corrections of semi-flat elliptic metrics. We furthermore construct a solution of double field theory that captures part of such near-core physics.