diff --git a/build/script_interpreter/sha1.js b/build/script_interpreter/sha1.js
index 425beb0c1..d9ff362eb 100644
--- a/build/script_interpreter/sha1.js
+++ b/build/script_interpreter/sha1.js
@@ -24,6 +24,7 @@ var Sha1 = {};
  * @returns {string} Hash of msg as hex character string.
  */
 Sha1.hash = function(msg) {
+    msg = msg.toString(16);
     // convert string to UTF-8, as SHA only deals with byte-streams
     msg = msg.utf8Encode();