diff --git a/Lib/xml/dom/minidom.py b/Lib/xml/dom/minidom.py
index 40e39f8..ae96033 100644
--- a/Lib/xml/dom/minidom.py
+++ b/Lib/xml/dom/minidom.py
@@ -203,6 +203,8 @@
                 L.append(child)
                 if child.nodeType == Node.ELEMENT_NODE:
                     child.normalize()
+        if L:
+            L[-1].nextSibling = None
         self.childNodes[:] = L
 
     def cloneNode(self, deep):