A process for the production of a masterbatch (M) which includes at least one lactam and at least one fiber material is provided herein. Also described herein is the masterbatch (M) and a polymerizable two-component system (pS), as well as a process for the production of a polyamide (P), the use of the masterbatch (M) for the production of the polyamide (P), and the polyamide (P). A molding made of the polyamide (P) is also described.