diff --git a/mercurial/bookmarks.py b/mercurial/bookmarks.py
--- a/mercurial/bookmarks.py
+++ b/mercurial/bookmarks.py
@@ -192,13 +192,12 @@ def update(repo, parents, node):
         return False
 
     if marks[cur] in parents:
-        old = repo[marks[cur]]
         new = repo[node]
         divs = [repo[b] for b in marks
                 if b.split('@', 1)[0] == cur.split('@', 1)[0]]
         anc = repo.changelog.ancestors([new.rev()])
         deletefrom = [b.node() for b in divs if b.rev() in anc or b == new]
-        if old.descendant(new):
+        if validdest(repo, repo[marks[cur]], new):
             marks[cur] = new.node()
             update = True
 
diff --git a/tests/test-update-branches.t b/tests/test-update-branches.t
--- a/tests/test-update-branches.t
+++ b/tests/test-update-branches.t
@@ -229,13 +229,16 @@ the bookmark (issue4015)
   $ hg bookmarks
    * bm                        5:ff252e8273df
 
-Test that 4 is detected as the no-argument destination from 3
+Test that 4 is detected as the no-argument destination from 3 and also moves
+the bookmark with it
   $ hg up --quiet 0          # we should be able to update to 3 directly
   $ hg up --quiet --hidden 3 # but not implemented yet.
+  $ hg book -f bm
   $ hg up
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
-  $ hg id
-  d047485b3896+ (b1)
+  updating bookmark bm
+  $ hg book
+   * bm                        4:d047485b3896
 
 Test that 5 is detected as a valid destination from 1
   $ hg up --quiet 0          # we should be able to update to 3 directly