diff --git a/tiddlyfox/extension/content/overlay.js b/tiddlyfox/extension/content/overlay.js
index d2e54d3fc..44e9fcbb7 100644
--- a/tiddlyfox/extension/content/overlay.js
+++ b/tiddlyfox/extension/content/overlay.js
@@ -105,7 +105,8 @@ var TiddlyFox = {
 	isTiddlyWikiClassic: function(doc,win) {
 		// Test whether the document is a TiddlyWiki (we don't have access to JS objects in it)
 		return (doc.location.protocol === "file:") &&
-			(doc.scripts[0].id === "versionArea");
+			doc.getElementById("storeArea") &&
+			(/TiddlyWiki/.test(doc.scripts[0].text));
 	},
 
 	isTiddlyWiki5: function(doc,win) {
diff --git a/tiddlyfox/extension/install.rdf b/tiddlyfox/extension/install.rdf
index 1cc81be4b..da7588e36 100644
--- a/tiddlyfox/extension/install.rdf
+++ b/tiddlyfox/extension/install.rdf
@@ -6,7 +6,7 @@
   
     <em:id>tiddlyfox@tiddlywiki.org</em:id>
     <em:name>TiddlyFox extension for Firefox</em:name>
-    <em:version>1.0alpha3</em:version>
+    <em:version>1.0alpha4</em:version>
     <em:description>A Firefox extension to enable TiddlyWiki to save changes directly to the file system.</em:description>
     <em:creator>Jeremy Ruston</em:creator>
     <em:homepageURL>https://five.tiddlywiki.com/tiddlyfox</em:homepageURL>
diff --git a/tiddlyfox/extension/tiddlyfox.xpi b/tiddlyfox/extension/tiddlyfox.xpi
index 82f127b28..d2f9e9eb9 100644
Binary files a/tiddlyfox/extension/tiddlyfox.xpi and b/tiddlyfox/extension/tiddlyfox.xpi differ