diff --git a/misc/yosysjs/demo03.html b/misc/yosysjs/demo03.html
index 36cc6cf4..c9386aee 100644
--- a/misc/yosysjs/demo03.html
+++ b/misc/yosysjs/demo03.html
@@ -24,16 +24,18 @@ endmodule
 	<h1>YosysJS Example Application #03</h1>
 	<b>Your mission:</b> Create a behavioral Verilog model for the following circuit:
 	<p/>
-	<svg id="schem" width="800"></svg>
-	<p/>
-	<pre id="code" style="width: 800px; border:2px solid #000; padding: 0.5em;"><span class="noedit">module top(input clk, reset, input [7:0] A, output reg [7:0] Y);
-  always @(posedge clock) begin</span><span class="edit" contenteditable="true">
-    Y &lt;= A | {4{reset}};
-  </span><span class="noedit">end
-endmodule</span></pre><p/>
-	<input type="button" value="Check Model" onclick="check_model()"> <span id="checkmessage"></span>
-	<p/>
-	<p id="wave">&nbsp;</p>
+	<div id="main" style="visibility: hidden">
+		<svg id="schem" width="800"></svg>
+		<p/>
+		<pre id="code" style="width: 800px; border:2px solid #000; padding: 0.5em;"><span class="noedit">module top(input clk, reset, input [7:0] A, output reg [7:0] Y);
+	  always @(posedge clock) begin</span><span class="edit" contenteditable="true">
+	    Y &lt;= A | {4{reset}};
+	  </span><span class="noedit">end
+	endmodule</span></pre><p/>
+		<input type="button" value="Check Model" onclick="check_model()"> <span id="checkmessage"></span>
+		<p/>
+		<p id="wave">&nbsp;</p>
+	</div>
 	<script type="text/javascript">
 		function on_ys_ready() {
 			ys.write_file('golden.v', document.getElementById('golden_verilog').textContent);
@@ -42,6 +44,7 @@ endmodule</span></pre><p/>
 			YosysJS.dot_into_svg(ys.read_file('show.dot'), 'schem');
 			document.getElementById('popup').style.visibility = 'hidden';
 			document.getElementById('popupmsg').textContent = 'Please wait..';
+			document.getElementById('main').style.visibility = 'visible';
 		}
 		function check_model() {
 			function work() {
diff --git a/misc/yosysjs/yosysjs.js b/misc/yosysjs/yosysjs.js
index b0205bf6..2c78451d 100644
--- a/misc/yosysjs/yosysjs.js
+++ b/misc/yosysjs/yosysjs.js
@@ -1,6 +1,7 @@
 var YosysJS = new function() {
 	this.script_element = document.currentScript;
 	this.viz_element = undefined;
+	this.viz_ready = true;
 
 	this.url_prefix = this.script_element.src.replace(/[^/]+$/, '')
 
@@ -12,9 +13,21 @@ var YosysJS = new function() {
 		this.viz_element.style.display = 'none'
 		document.body.appendChild(this.viz_element);
 
-		this.viz_element.contentWindow.document.open()
-		this.viz_element.contentWindow.document.write('<script type="text/javascript" src="' + this.url_prefix + 'viz.js"></' + 'script>');
-		this.viz_element.contentWindow.document.close()
+		this.viz_element.contentWindow.document.open();
+		this.viz_element.contentWindow.document.write('<script type="text/javascript" onload="viz_ready = true;" src="' + this.url_prefix + 'viz.js"></' + 'script>');
+		this.viz_element.contentWindow.document.close();
+
+		var that = this;
+		function check_viz_ready() {
+			if (that.viz_element.contentWindow.viz_ready) {
+				console.log("YosysJS: Successfully loaded Viz.");
+				that.viz_ready = true;
+			} else
+				window.setTimeout(check_viz_ready, 100);
+		}
+
+		this.viz_ready = false;
+		window.setTimeout(check_viz_ready, 100);
 	}
 
 	this.dot_to_svg = function(dot_text) {
@@ -40,6 +53,7 @@ var YosysJS = new function() {
 
 	this.create = function(reference_element, on_ready) {
 		var ys = new Object();
+		ys.YosysJS = this;
 		ys.init_script = "";
 		ys.ready = false;
 		ys.verbose = false;
@@ -185,13 +199,13 @@ var YosysJS = new function() {
 			} catch (e) { }
 		}
 
-		doc.open()
+		doc.open();
 		doc.write('<script type="text/javascript" src="' + this.url_prefix + 'yosys.js"></' + 'script>');
-		doc.close()
+		doc.close();
 
 		if (on_ready || ys.init_script) {
 			function check_ready() {
-				if (ys.ready) {
+				if (ys.ready && ys.YosysJS.viz_ready) {
 					if (ys.init_script) {
 						ys.write_file("/script.ys", ys.init_script);
 						ys.run("script /script.ys");