diff --git a/main.go b/main.go
index db871a0..c3e8257 100644
--- a/main.go
+++ b/main.go
@@ -158,7 +158,7 @@ func thompson(re string) *State {
 			s2 := &State{}
 			s2.transitions = make(map[int][]*State)
 			s2.content = EPSILON
-			s2.output = make([]*State, 0)
+			s2.output = append(s2.output, s2)
 			s2.isEmpty = true
 			s3 := alternate(s1, s2)
 			nfa = append(nfa, s3)