diff --git a/index.js b/index.js
index 732e62c..ff613cc 100644
--- a/index.js
+++ b/index.js
@@ -286,11 +286,9 @@ function decodeString(str) {
 
   // look up attachments if type binary
   if (exports.BINARY_EVENT === p.type || exports.BINARY_ACK === p.type) {
-    var buf = '';
-    while (str.charAt(++i) !== '-') {
-      buf += str.charAt(i);
-      if (i == str.length) break;
-    }
+    var start = i + 1;
+    while (str.charAt(++i) !== '-' && i != str.length) {}
+    var buf = str.substring(start, i);
     if (buf != Number(buf) || str.charAt(i) !== '-') {
       throw new Error('Illegal attachments');
     }
@@ -299,13 +297,13 @@ function decodeString(str) {
 
   // look up namespace (if any)
   if ('/' === str.charAt(i + 1)) {
-    p.nsp = '';
+    var start = i + 1;
     while (++i) {
       var c = str.charAt(i);
       if (',' === c) break;
-      p.nsp += c;
       if (i === str.length) break;
     }
+    p.nsp = str.substring(start, i);
   } else {
     p.nsp = '/';
   }