diff --git a/hgext/rebase.py b/hgext/rebase.py
index fd3d8eb7f5459b1700f7794a9b2f42a23df0de5a_aGdleHQvcmViYXNlLnB5..361bccce566afe250c8d258f770a908713b2d13f_aGdleHQvcmViYXNlLnB5 100644
--- a/hgext/rebase.py
+++ b/hgext/rebase.py
@@ -721,7 +721,7 @@
     finally:
         release(lock, wlock)
 
-def _definesets(ui, repo, destf=None, srcf=None, basef=None, revf=[],
+def _definesets(ui, repo, destf=None, srcf=None, basef=None, revf=None,
                 destspace=None):
     """use revisions argument to define destination and rebase set
     """
@@ -725,6 +725,8 @@
                 destspace=None):
     """use revisions argument to define destination and rebase set
     """
+    revf = revf or []
+
     # destspace is here to work around issues with `hg pull --rebase` see
     # issue5214 for details
     if srcf and basef: