diff --git a/js/securityLib/base64.js b/js/securityLib/base64.js
index b6fd7b7..cc582e2 100644
--- a/js/securityLib/base64.js
+++ b/js/securityLib/base64.js
@@ -29,7 +29,7 @@
   var slop;
   for(i = 0; i < s.length; ++i) {
     if(s.charAt(i) == b64pad) break;
-    v = b64map.indexOf(s.charAt(i));
+    var v = b64map.indexOf(s.charAt(i));
     if(v < 0) continue;
     if(k == 0) {
       ret += int2char(v >> 2);