diff --git a/mercurial/revlog.py b/mercurial/revlog.py
--- a/mercurial/revlog.py
+++ b/mercurial/revlog.py
@@ -1635,7 +1635,7 @@ class revlog(object):
                         fh = ifh
                     else:
                         fh = dfh
-                    ptext = self.revision(rev, _df=fh)
+                    ptext = self.revision(rev, _df=fh, raw=True)
                     delta = mdiff.textdiff(ptext, t)
             header, data = self.compress(delta)
             deltalen = len(header) + len(data)
diff --git a/tests/test-revlog-raw.py.out b/tests/test-revlog-raw.py.out
--- a/tests/test-revlog-raw.py.out
+++ b/tests/test-revlog-raw.py.out
@@ -1,1 +1,2 @@
-abort: crashed: integrity check failed on _testrevlog.i:11
+local test passed
+abort: crashed: invalid patch