diff --git a/modules/l4tls/matcher.go b/modules/l4tls/matcher.go
index bf0b2b3..eaea266 100644
--- a/modules/l4tls/matcher.go
+++ b/modules/l4tls/matcher.go
@@ -270,8 +270,8 @@ func unmarshalCaddyfileMatchRemoteIP(d *caddyfile.Dispenser) (*caddytls.MatchRem
 		rangesRaw, notRangesRaw := make([]string, 0, d.CountRemainingArgs()), make([]string, 0, d.CountRemainingArgs())
 		for d.NextArg() {
 			val := d.Val()
-			if val[0] == '!' {
-				notRangesRaw = append(notRangesRaw, val)
+			if len(val) > 1 && val[0] == '!' {
+				notRangesRaw = append(notRangesRaw, val[1:])
 			} else {
 				rangesRaw = append(rangesRaw, val)
 			}