diff --git a/boards/static/js/refpopup.js b/boards/static/js/refpopup.js
--- a/boards/static/js/refpopup.js
+++ b/boards/static/js/refpopup.js
@@ -27,6 +27,10 @@ function showPostPreview(e) {
     //ref id
     var pNum = $(this).text().match(/\d+/);
 
+    if (pNum.length == 0) {
+	return;
+    }
+
     //position
     //var x = e.clientX + (doc.documentElement.scrollLeft || doc.body.scrollLeft) - doc.documentElement.clientLeft + 1;
     //var y = e.clientY + (doc.documentElement.scrollTop || doc.body.scrollTop) - doc.documentElement.clientTop;