diff --git a/nfa.go b/nfa.go
index 31cdcfc..8b98ee7 100644
--- a/nfa.go
+++ b/nfa.go
@@ -136,7 +136,7 @@ func (s State) checkAssertion(str []rune, idx int) bool {
 			strToMatch = string(runesToMatch)
 		}
 
-		matchIndices := findAllMatches(Reg{startState, startState.lookaroundNumCaptureGroups}, strToMatch)
+		matchIndices := findAllMatches(Reg{startState, s.lookaroundNumCaptureGroups}, strToMatch)
 
 		numMatchesFound := 0
 		for _, matchIdx := range matchIndices {