diff --git a/lib/underscore.string.js b/lib/underscore.string.js
index 7be1bb32..a32e4758 100644
--- a/lib/underscore.string.js
+++ b/lib/underscore.string.js
@@ -417,23 +417,23 @@
       str = str == null ? '' : String(str);
       length = ~~length;
 
-      var padlen  = 0;
+      if(length <= str.length) return str;
 
       if (!padStr)
         padStr = ' ';
       else if (padStr.length > 1)
         padStr = padStr.charAt(0);
+      
+      var padlen = length - str.length;
 
       switch(type) {
         case 'right':
-          padlen = length - str.length;
           return str + strRepeat(padStr, padlen);
         case 'both':
-          padlen = length - str.length;
-          return strRepeat(padStr, Math.ceil(padlen/2)) + str
-                  + strRepeat(padStr, Math.floor(padlen/2));
+          var halfPadlen = ~~(padlen/2),
+              repeatedPadStr = strRepeat(padStr, halfPadlen);
+          return  repeatedPadStr + (padlen % 2 ? padStr : '') + str + repeatedPadStr;
         default: // 'left'
-          padlen = length - str.length;
           return strRepeat(padStr, padlen) + str;
         }
     },