diff --git a/tiddlyfox/extension/content/overlay.js b/tiddlyfox/extension/content/overlay.js
index d9d0bb4fe..7787dd142 100644
--- a/tiddlyfox/extension/content/overlay.js
+++ b/tiddlyfox/extension/content/overlay.js
@@ -85,7 +85,8 @@ var TiddlyFox = {
 
 	isTiddlyWiki: function(doc,win) {
 		// Test whether the document is a TiddlyWiki (we don't have access to JS objects in it)
-		return (doc.scripts[0].id === "versionArea");
+		return (doc.location.protocol === "file:") &&
+			(doc.scripts[0].id === "versionArea");
 	}
 
 };
diff --git a/tiddlyfox/extension/tiddlyfox.xpi b/tiddlyfox/extension/tiddlyfox.xpi
index 1987058de..0e2fccad1 100644
Binary files a/tiddlyfox/extension/tiddlyfox.xpi and b/tiddlyfox/extension/tiddlyfox.xpi differ