diff --git a/app/js/diceware.js b/app/js/diceware.js
index 2cea62a..64388bb 100644
--- a/app/js/diceware.js
+++ b/app/js/diceware.js
@@ -58,14 +58,14 @@ Diceware.prototype.getWords = function(words) {
 
 Diceware.prototype.random = function (min, max) {
     var rval = 0;
-    var range = max - min;
+    var range = max - min + 1;
     
     var bits_needed = Math.ceil(Math.log2(range));
     if (bits_needed > 53) {
       throw new Exception("We cannot generate numbers larger than 53 bits.");
     }
     var bytes_needed = Math.ceil(bits_needed / 8);
-    var mask = Math.pow(2, bits_needed) - 1; 
+    var mod = Math.pow(2, bits_needed); 
     // 7776 -> (2^13 = 8192) -1 == 8191 or 0x00001111 11111111
     
     // Create byte array and fill with N random numbers
@@ -78,8 +78,8 @@ Diceware.prototype.random = function (min, max) {
       p -= 8;   
     }
     
-    // Use & to apply the mask and reduce the number of recursive lookups
-    rval = rval & mask;
+    // Use % to reduce the number of recursive lookups
+    rval = rval % mod;
     
     if (rval >= range) {
       // Integer out of acceptable range
@@ -93,6 +93,6 @@ Diceware.prototype.getSingleWord = function() {
   if (!window.crypto || !window.crypto.getRandomValues) {
     return null;
   }
-  var index = this.random(0, this.wordlist.length);
+  var index = this.random(0, this.wordlist.length - 1);
   return this.wordlist[index];
 };