diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -314,7 +314,7 @@ class revlogoldio(object):
 
         return index, nodemap, None
 
-    def packentry(self, entry, node, version):
+    def packentry(self, entry, node, version, rev):
         e2 = (getoffset(entry[0]), entry[1], entry[3], entry[4],
               node(entry[5]), node(entry[6]), entry[7])
         return _pack(indexformatv0, *e2)
@@ -388,9 +388,9 @@ class revlogio(object):
 
         return index, nodemap, cache
 
-    def packentry(self, entry, node, version):
+    def packentry(self, entry, node, version, rev):
         p = _pack(indexformatng, *entry)
-        if not entry[3] and not getoffset(entry[0]) and entry[5] == nullrev:
+        if rev == 0:
             p = _pack(versionformat, version) + p[4:]
         return p
 
@@ -972,7 +972,7 @@ class revlog(object):
         self.version &= ~(REVLOGNGINLINEDATA)
         self._inline = False
         for i in xrange(self.count()):
-            e = self._io.packentry(self.index[i], self.node, self.version)
+            e = self._io.packentry(self.index[i], self.node, self.version, i)
             fp.write(e)
 
         # if we don't call rename, the temp file will never replace the
@@ -1027,7 +1027,7 @@ class revlog(object):
         self.index.insert(-1, e)
         self.nodemap[node] = curr
 
-        entry = self._io.packentry(e, self.node, self.version)
+        entry = self._io.packentry(e, self.node, self.version, curr)
         if not self._inline:
             transaction.add(self.datafile, offset)
             transaction.add(self.indexfile, curr * len(entry))
@@ -1179,7 +1179,7 @@ class revlog(object):
                      link, self.rev(p1), self.rev(p2), node)
                 self.index.insert(-1, e)
                 self.nodemap[node] = r
-                entry = self._io.packentry(e, self.node, self.version)
+                entry = self._io.packentry(e, self.node, self.version, r)
                 if self._inline:
                     ifh.write(entry)
                     ifh.write(cdelta)
diff --git a/tests/test-revlog-packentry b/tests/test-revlog-packentry
new file mode 100755
--- /dev/null
+++ b/tests/test-revlog-packentry
@@ -0,0 +1,14 @@
+#!/bin/sh
+
+hg init repo
+cd repo
+
+touch foo
+hg ci -Am 'add foo'
+
+hg up -C null
+# this should be stored as a delta against rev 0
+echo foo bar baz > foo
+hg ci -Am 'add foo again'
+
+hg debugindex .hg/store/data/foo.i
diff --git a/tests/test-revlog-packentry.out b/tests/test-revlog-packentry.out
new file mode 100644
--- /dev/null
+++ b/tests/test-revlog-packentry.out
@@ -0,0 +1,6 @@
+adding foo
+0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+adding foo
+   rev    offset  length   base linkrev nodeid       p1           p2
+     0         0       0      0       0 b80de5d13875 000000000000 000000000000
+     1         0      24      0       1 0376abec49b8 000000000000 000000000000