Two-component or multi-component fixing mortar, based on a free-radical-hardening unsaturated reactive resin, for embedding anchoring means in mortar in holes or crevices, which fixing mortar includes silanes which may or may not have reactive groups capable of participating in the polymerization with a synthetic resin based on free-radical-hardening unsaturated reactive resins but do in any case have Si-bonded hydrolysable groups, and, physically separate therefrom, a hardener.