2to3's api should be considered unstable
diff --git a/Doc/library/2to3.rst b/Doc/library/2to3.rst
index 8040124..e603b45 100644
--- a/Doc/library/2to3.rst
+++ b/Doc/library/2to3.rst
@@ -95,4 +95,10 @@
 .. moduleauthor:: Guido van Rossum
 .. moduleauthor:: Collin Winter
 
+
+.. warning::
+
+   The :mod:`lib2to3` API should be considered unstable and may change
+   drastically in the future.
+
 .. XXX What is the public interface anyway?