In this work we study type IIB Calabi-Yau orientifold compactifications in the presence of space-time filling D7-branes and O7-planes. In particular, we conclude that $alpha^2 g_s$-corrections to their DBI actions lead to a modification of the four-dimensional $mathcal{N}=1$ Kahler potential and coordinates. We focus on the one-modulus case of the geometric background i.e. $h^{1,1}=1$ where we find that the $alpha^2 g_s$-correction is of topological nature. It depends on the first Chern form of the four-cycle of the Calabi-Yau orientifold which is wrapped by the D7-branes and O7-plane. This is in agreement with our previous F-theory analysis and provides further evidence for a potential breaking of the no-scale structure at order $alpha^2 g_s$. Corrected background solutions for the dilaton, the warp-factor as well as the internal space metric are derived. Additionally, we briefly discuss $alpha$-corrections from other D$p$-branes.
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