diff --git a/regex/matching.go b/regex/matching.go
index 559b88e..b82a60f 100644
--- a/regex/matching.go
+++ b/regex/matching.go
@@ -82,7 +82,7 @@ func takeZeroState(states []*nfaState, numGroups int, idx int) (rtv []*nfaState,
 		}
 	}
 	for _, state := range rtv {
-		if len(state.transitions[EPSILON]) > 0 {
+		if len(state.transitions[epsilon]) > 0 {
 			return rtv, true
 		}
 	}