diff --git a/hgext3rd/undo.py b/hgext3rd/undo.py
--- a/hgext3rd/undo.py
+++ b/hgext3rd/undo.py
@@ -599,4 +599,15 @@
 
 def _getrevlog(repo, filename):
     path = 'undolog/' + filename
-    return revlog.revlog(repo.svfs, path)
+    try:
+        return revlog.revlog(repo.svfs, path)
+    except error.RevlogError:
+        # corruption: for now, we can simply nuke all files
+        # TODO: log to Scuba
+        repo.ui.debug("cought revlog error. %s was probably corrupted", path)
+        repo.svfs.rmtree('undolog')
+        repo.svfs.makedirs('undolog')
+        # if we get the error a second time
+        # then someone is actively messing with these files
+        return revlog.revlog(repo.svfs, path)
+
diff --git a/tests/test-undo.t b/tests/test-undo.t
--- a/tests/test-undo.t
+++ b/tests/test-undo.t
@@ -403,3 +403,11 @@
   > tweakdefaults =!
   > fbamend =!
   > EOF
+
+File corruption handling
+  $ cat >> .hg/store/undolog/index.i << EOF
+  > corrupted
+  > EOF
+  $ hg st
+  $ hg debugundohistory -l
+  0:  -- gap in log --