diff --git a/transcoders.go b/transcoders.go
index e1f5b27..89da695 100644
--- a/transcoders.go
+++ b/transcoders.go
@@ -14,8 +14,11 @@ import (
 )
 
 type Transcoder interface {
+	// Validates and encodes to bytes a multiaddr that's in the string representation.
 	StringToBytes(string) ([]byte, error)
+	// Validates and decodes to a string a multiaddr that's in the bytes representation.
 	BytesToString([]byte) (string, error)
+	// Validates bytes when parsing a multiaddr that's already in the bytes representation.
 	ValidateBytes([]byte) error
 }
 
@@ -63,6 +66,9 @@ func ip6zoneStB(s string) ([]byte, error) {
 	if len(s) == 0 {
 		return nil, fmt.Errorf("empty ip6zone")
 	}
+	if strings.Contains(s, "/") {
+		return nil, fmt.Errorf("IPv6 zone ID contains '/': %s", s)
+	}
 	return []byte(s), nil
 }