Model checking tools based on the iterative refinement of predicate abstraction (e.g., Slam and Blast) often feature a specification language for expressing complex behavior rules. The source code under verification is instrumented by artificial variables and statements in order to transform the problem of checking such a rule into the problem of program location reachability. This way, the source code get bloated and additional predicates have to be discovered and tracked during the verification. We suggest that a significant performance improvement can be achieved by tracking state of the behavior rules aside from the source code instead of instrumenting them. We have implemented an extension to Blast, which accepts a specification language (a simplified version of behavior protocols), and checks its validity without modifying the input source code. An experiment with two Linux kernel drivers confirms the performance gain using the extension.