diff --git a/mercurial/merge.py b/mercurial/merge.py
--- a/mercurial/merge.py
+++ b/mercurial/merge.py
@@ -416,11 +416,15 @@ def manifestmerge(repo, wctx, p2, pa, br
             continue
         if n1 and n2:
             if f not in ma:
-                # Note: f as ancestor is wrong - we can't really make a 3-way
-                # merge without an ancestor file.
-                fa = copy.get(f, f)
-                actions['m'].append((f, (f, f, fa, False, pa.node()),
-                               "both created"))
+                fa = copy.get(f, None)
+                if fa is not None:
+                    actions['m'].append((f, (f, f, fa, False, pa.node()),
+                                   "both renamed from " + fa))
+                else:
+                    # Note: f as ancestor is wrong - we can't really make a
+                    # 3-way merge without an ancestor file.
+                    actions['m'].append((f, (f, f, f, False, pa.node()),
+                                   "both created"))
             else:
                 a = ma[f]
                 fla = ma.flags(f)
diff --git a/tests/test-rename-merge2.t b/tests/test-rename-merge2.t
--- a/tests/test-rename-merge2.t
+++ b/tests/test-rename-merge2.t
@@ -343,7 +343,7 @@ args:
    ancestor: 924404dff337, local: 62e7bf090eba+, remote: 49b6d8032493
    preserving b for resolve of b
    preserving rev for resolve of rev
-   b: both created -> m
+   b: both renamed from a -> m
   updating: b 1/2 files (50.00%)
   picked tool 'python ../merge' for b (binary False symlink False)
   merging b