This paper describes a technique to apply formal methods to verify protocols for mobile ad hoc networks. In contrast to other related proposals, our solution does not attempt to model any particular network configuration. Instead, our solution focuses on the possible implications caused by network configurations to the behavior of a routing protocol for MANETs. Following this strategy we were able to find design errors in some well established protocols. The proposed technique uses formal verification, more specifically model checking, to detect, in a simple way, problems such as routing loops, delivery message failures and errors in the protocol state machine.