diff --git a/core/js/Story.js b/core/js/Story.js
index 9a0b57b..4f6ad42 100644
--- a/core/js/Story.js
+++ b/core/js/Story.js
@@ -12,6 +12,10 @@ function Story(containerId,idPrefix)
 	this.highlightRegExp = null;
 	//# generate tiddler ID
 	this.tiddlerId = function(title) {
+		var id = this.idPrefix + title;
+		while(document.getElementById(id)) { //# ensure ID is unique
+			id += "_";
+		}
 		return this.idPrefix + title;
 	};
 	this.containerId = function() {