diff --git a/lib/x11/unpackbuffer.js b/lib/x11/unpackbuffer.js
index 3d2a4e5..410c8f1 100644
--- a/lib/x11/unpackbuffer.js
+++ b/lib/x11/unpackbuffer.js
@@ -26,7 +26,7 @@ module.exports.addUnpack = function(Buffer)
             case 'S':
                 var b1 = this[offset++];
                 var b2 = this[offset++];
-                this.data.push(b2*256+b1);
+                data.push(b2*256+b1);
                 break;
             case 'L':
                 var b1 = this[offset++];
@@ -43,4 +43,4 @@ module.exports.addUnpack = function(Buffer)
         }
         return data;
     }
-}
\ No newline at end of file
+}