diff --git a/jsmpg.js b/jsmpg.js
index 71968c51..d7e7d737 100755
--- a/jsmpg.js
+++ b/jsmpg.js
@@ -23,6 +23,7 @@ var jsmpeg = window.jsmpeg = function(url, opts) {
 	this.blockData = new Int32Array(64);
 	this.zeroBlockData = new Int32Array(64);
 	this.fillArray(this.zeroBlockData, 0);
+	this.intraFrames = [];
 
 	// Use WebGL for YCbCrToRGBA conversion if possible (much faster)
 	if (!opts.forceCanvas2D && this.initWebGL()) {