diff --git a/main.go b/main.go
index cad3e9a..4d77a06 100644
--- a/main.go
+++ b/main.go
@@ -21,11 +21,7 @@ import (
 )
 
 const (
-	letterBytes   = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789" // Base strings for randStringBytesMaskImprSrc
-	letterIdxBits = 6                                                                // 6 bits to represent a letter index
-	letterIdxMask = 1<<letterIdxBits - 1                                             // All 1-bits, as many as letterIdxBits
-	letterIdxMax  = 63 / letterIdxBits                                               // # of letter indices fitting in 63 bits
-	appVersion    = "1.3.0"
+	appVersion = "1.3.0"
 )
 
 var (