diff --git a/hgext3rd/undo.py b/hgext3rd/undo.py
--- a/hgext3rd/undo.py
+++ b/hgext3rd/undo.py
@@ -207,7 +207,7 @@
     revstring = "\n".join(sorted('%s %s' % (k, v) for k, v in nodes.items()))
     return writelog(repo, tr, "index.i", revstring)
 
-def _logundoredoindex(repo, tr, reverseindex):
+def _logundoredoindex(repo, reverseindex):
     rlog = _getrevlog(repo, 'index.i')
     hexnode = hex(rlog.node(_invertindex(rlog, reverseindex)))
     return repo.vfs.write("undolog/redonode", str(hexnode))
@@ -539,16 +539,17 @@
     keep = opts.get("keep")
     preview = opts.get("preview")
 
+    if relativeundo:
+        reverseindex = _computerelative(repo, reverseindex)
+
     if preview:
-        _preview(ui, repo, **opts)
+        _preview(ui, repo, reverseindex, **opts)
         return
 
     with repo.wlock(), repo.lock(), repo.transaction("undo"):
         cmdutil.checkunfinished(repo)
         cmdutil.bailifchanged(repo)
         repo = repo.unfiltered()
-        if relativeundo:
-            reverseindex = _computerelative(repo, reverseindex)
         if not (opts.get("force") or _gapcheck(repo, reverseindex)):
             raise error.Abort(_("attempted risky undo across"
                                 " missing history"))
@@ -556,10 +557,12 @@
         # store undo data
         # for absolute undos, think of this as a reset
         # for relative undos, think of this as an update
-        _logundoredoindex(repo, repo.currenttransaction(), reverseindex)
+        _logundoredoindex(repo, reverseindex)
 
 @command('redo', [
     ('n', 'index', 1, _("how many commands to redo")),
+    ('p', 'preview', False, _("see smartlog like preview of future redo "
+                              "state")),
 ])
 def redo(ui, repo, *args, **opts):
     """ perform a redo
@@ -573,13 +576,18 @@
     """
     reverseindex = -1 * abs(opts.get("index"))
     reverseindex = _computerelative(repo, reverseindex)
+    preview = opts.get("preview")
+
+    if preview:
+        _preview(ui, repo, reverseindex, **opts)
+        return
 
     with repo.wlock(), repo.lock(), repo.transaction("redo"):
         cmdutil.checkunfinished(repo)
         cmdutil.bailifchanged(repo)
         repo = repo.unfiltered()
         _undoto(ui, repo, reverseindex)
-        _logundoredoindex(repo, repo.currenttransaction(), reverseindex)
+        _logundoredoindex(repo, reverseindex)
 
 def _undoto(ui, repo, reverseindex, keep=False):
     # undo to specific reverseindex
@@ -706,7 +714,7 @@
         ctxts = repo.set(rev)
         inhibit.revive(ctxts)
 
-def _preview(ui, repo, **opts):
+def _preview(ui, repo, reverseindex, **opts):
     # Print smartlog like preview of undo
     # Input:
     #   ui:
@@ -715,35 +723,40 @@
     # Output:
     #   None
     # Requires smartlog extension
+    savedindex = _computerelative(repo, 0)
     try:
         smartlog = extensions.find('smartlog')
     except KeyError:
         raise error.Abort(_('undo requires smartlog to work properly'))
-    reverseindex = opts.get("index")
-    opts["template"] = "{undopreview}"
-    reverseindex = _computerelative(repo, reverseindex)
-    revstring = revsetlang.formatspec("olddraft(%d)", reverseindex)
-    revs = set()
+    # overwrite undoredo with fake index, so that relative calls of 1 will
+    # return the index we want
+    _logundoredoindex(repo, reverseindex - 1)
     try:
-        revs.update(repo.revs(revstring))
-    except IndexError:
-        raise error.Abort(_("can't undo: no data past this point"))
-        return
-    repo.filtered('visible')
-    revs.update(repo.revs("draft()"))
-    repo = repo.unfiltered()
-    revs = sorted(list(revs), reverse=True)
-    overrides = {}
-    if ui.config('experimental', 'graphstyle.grandparent') == '|':
-        overrides[('experimental', 'graphstyle.grandparent')] = '2.'
-    with ui.configoverride(overrides, 'smartlog'):
-        masterstring = opts.get('master')
-        masterrevset = smartlog._masterrevset(ui, repo, masterstring)
-        masterrev = smartlog._masterrev(repo, masterrevset)
-        revdag = smartlog.getdag(ui, repo, revs, masterrev)
-        displayer = cmdutil.show_changeset(ui, repo, opts, buffered=True)
-        cmdutil.displaygraph(
-            ui, repo, revdag, displayer, graphmod.asciiedges, None, None)
+        opts["template"] = "{undopreview}"
+        revstring = revsetlang.formatspec("olddraft(%d)", reverseindex)
+        revs = set()
+        try:
+            revs.update(repo.revs(revstring))
+        except IndexError:
+            raise error.Abort(_("can't undo: no data past this point"))
+            return
+        repo.filtered('visible')
+        revs.update(repo.revs("draft()"))
+        repo = repo.unfiltered()
+        revs = sorted(list(revs), reverse=True)
+        overrides = {}
+        if ui.config('experimental', 'graphstyle.grandparent') == '|':
+            overrides[('experimental', 'graphstyle.grandparent')] = '2.'
+        with ui.configoverride(overrides, 'smartlog'):
+            masterstring = opts.get('master')
+            masterrevset = smartlog._masterrevset(ui, repo, masterstring)
+            masterrev = smartlog._masterrev(repo, masterrevset)
+            revdag = smartlog.getdag(ui, repo, revs, masterrev)
+            displayer = cmdutil.show_changeset(ui, repo, opts, buffered=True)
+            cmdutil.displaygraph(
+                ui, repo, revdag, displayer, graphmod.asciiedges, None, None)
+    finally:# always restore undoredo
+        _logundoredoindex(repo, savedindex)
     return
 
 # Tools