diff --git a/src/app/display-buffer-marker.coffee b/src/app/display-buffer-marker.coffee
index 0e318bd71..5027441f7 100644
--- a/src/app/display-buffer-marker.coffee
+++ b/src/app/display-buffer-marker.coffee
@@ -131,6 +131,9 @@ class DisplayBufferMarker
   isReversed: ->
     @bufferMarker.isReversed()
 
+  isValid: ->
+    @bufferMarker.isValid()
+
   destroy: ->
     delete @displayBuffer.markers[@id]
     @bufferMarker.destroy()