diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -1575,6 +1575,9 @@
         useful when reusing a revision not stored in this revlog (ex: received
         over wire, or read from an external bundle).
         """
+        if node == nullid:
+            raise RevlogError(_("%s: attempt to add null revision") %
+                              (self.indexfile))
         dfh = None
         if not self._inline:
             dfh = self.opener(self.datafile, "a+")