diff --git a/server/codec.go b/server/token.go
similarity index 97%
rename from server/codec.go
rename to server/token.go
index 1bd304f..a9d62a8 100644
--- a/server/codec.go
+++ b/server/token.go
@@ -40,7 +40,7 @@ const (
 func Token(length int) string {
 	result := ""
 	for i := 0; i < length; i++ {
-		x := rand.Intn(len(SYMBOLS))
+		x := rand.Intn(len(SYMBOLS) - 1)
 		result = string(SYMBOLS[x]) + result
 	}
 
diff --git a/server/codec_test.go b/server/token_test.go
similarity index 100%
rename from server/codec_test.go
rename to server/token_test.go