diff --git a/mercurial/pure/diffhelpers.py b/mercurial/diffhelpers.py
rename from mercurial/pure/diffhelpers.py
rename to mercurial/diffhelpers.py
--- a/mercurial/pure/diffhelpers.py
+++ b/mercurial/diffhelpers.py
@@ -1,4 +1,4 @@
-# diffhelpers.py - pure Python implementation of diffhelpers.c
+# diffhelpers.py - helper routines for patch
 #
 # Copyright 2009 Matt Mackall <mpm@selenic.com> and others
 #
diff --git a/mercurial/patch.py b/mercurial/patch.py
--- a/mercurial/patch.py
+++ b/mercurial/patch.py
@@ -28,6 +28,7 @@ from .node import (
 )
 from . import (
     copies,
+    diffhelpers,
     encoding,
     error,
     mail,
@@ -39,7 +40,6 @@ from . import (
     util,
     vfs as vfsmod,
 )
-from .pure import diffhelpers
 from .utils import (
     dateutil,
     procutil,