diff --git a/src/js/QuantizePVT.js b/src/js/QuantizePVT.js
index ef69bef..b849a58 100644
--- a/src/js/QuantizePVT.js
+++ b/src/js/QuantizePVT.js
@@ -50,7 +50,7 @@ QuantizePVT.LARGE_BITS = 100000;
 QuantizePVT.IXMAX_VAL = 8206;
 
 function QuantizePVT() {
-
+    var BitStream = require('./BitStream.js');
     var tak = null;
     var rv = null;
     var psy = null;