diff --git a/src/dom.coffee b/src/dom.coffee
index 75d3a2668c..6d9fd9fb61 100644
--- a/src/dom.coffee
+++ b/src/dom.coffee
@@ -218,6 +218,13 @@ DOM =
           DOM.removeNode(curNode.nextSibling)
       curNode = nextNode
 
+  isAncestor: (ancestor, node, inclusive = false) ->
+    return inclusive if ancestor == node
+    while node
+      return true if node == ancestor
+      node = node.parentNode
+    return false
+
   isIE: (maxVersion) ->
     version = document.documentMode
     return version and maxVersion >= version
diff --git a/src/line.coffee b/src/line.coffee
index 04697f2c4c..77c4663ef9 100644
--- a/src/line.coffee
+++ b/src/line.coffee
@@ -134,8 +134,8 @@ class Line extends LinkedList.Node
 
   rebuild: (force = false) ->
     if !force and @outerHTML? and @outerHTML == @node.outerHTML
-      if _.all(@leaves.toArray(), (leaf) ->
-        return leaf.node.parentNode?
+      if _.all(@leaves.toArray(), (leaf) =>
+        return DOM.isAncestor(@node, leaf.node)
       )
         return false
     @node = Normalizer.normalizeNode(@node)