diff --git a/microviewer/index.html b/microviewer/index.html
index 6a9b07a..5f5d204 100644
--- a/microviewer/index.html
+++ b/microviewer/index.html
@@ -792,7 +792,7 @@
           elems.addsegs.val("");
           elems.addsegs.blur();
           vol.hover_id = null;
-          Undo.push('select');
+          UNDO.push('select');
           render(true);
         });