The electrical properties of dopants in Si are of primary importance for the realization of electronic devices. Indium represents a promising p-type dopant whose electrical properties are improved by co-doping with C. From theoretical studies In and C are expected to pair in the Si matrix in order to lower the strain energy. In this contribution we provide the first direct experimental determination of the sites of In and In-C complexes in Si. The experiment is particularly challenging because, due to the low solubility of the impurity and to the high energy of the K edge, a particular experimental procedure is needed to separate the fluorescence signal from the substrate scattering.