--- a/hgext3rd/topic/stack.py	Mon Apr 04 00:22:20 2016 -0700
+++ b/hgext3rd/topic/stack.py	Mon Apr 04 00:28:03 2016 -0700
@@ -6,6 +6,7 @@
 from mercurial.i18n import _
 from mercurial import (
     error,
+    node,
     obsolete,
 )
 
@@ -27,7 +28,7 @@
         p1 = ctx.p1()
         if p1.obsolete():
             p1 = repo[_singlesuccessor(repo, p1)]
-        if p1.rev() != prev:
+        if p1.rev() != prev and p1.node() != node.nullid:
             entries.append((None, p1))
         entries.append((idx, ctx))
         prev = r