diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index 50ba2e4..be23ad2 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -310,6 +310,11 @@
 -p::
 --preserve-merges::
 	Instead of ignoring merges, try to recreate them.
++
+This uses the `--interactive` machinery internally, but combining it
+with the `--interactive` option explicitly is generally not a good
+idea unless you know what you are doing (see BUGS below).
+
 
 --root::
 	Rebase all commits reachable from <branch>, instead of
@@ -611,6 +616,28 @@
 case" recovery too!
 
 
+BUGS
+----
+The todo list presented by `--preserve-merges --interactive` does not
+represent the topology of the revision graph.  Editing commits and
+rewording their commit messages should work fine, but attempts to
+reorder commits tend to produce counterintuitive results.
+
+For example, an attempt to rearrange
+------------
+1 --- 2 --- 3 --- 4 --- 5
+------------
+to
+------------
+1 --- 2 --- 4 --- 3 --- 5
+------------
+by moving the "pick 4" line will result in the following history:
+------------
+	3
+       /
+1 --- 2 --- 4 --- 5
+------------
+
 Authors
 ------
 Written by Junio C Hamano <gitster@pobox.com> and