diff --git a/hgext/rebase.py b/hgext/rebase.py
--- a/hgext/rebase.py
+++ b/hgext/rebase.py
@@ -482,9 +482,10 @@ def buildstate(repo, dest, src, base, de
 
     if src:
         commonbase = repo[src].ancestor(repo[dest])
+        samebranch = repo[src].branch() == repo[dest].branch()
         if commonbase == repo[src]:
             raise util.Abort(_('source is ancestor of destination'))
-        if commonbase == repo[dest]:
+        if samebranch and commonbase == repo[dest]:
             raise util.Abort(_('source is descendant of destination'))
         source = repo[src].rev()
         if detach:
diff --git a/tests/test-rebase-named-branches.t b/tests/test-rebase-named-branches.t
new file mode 100644
--- /dev/null
+++ b/tests/test-rebase-named-branches.t
@@ -0,0 +1,171 @@
+  $ cat >> $HGRCPATH <<EOF
+  > [extensions]
+  > graphlog=
+  > rebase=
+  > 
+  > [alias]
+  > tglog = log -G --template "{rev}: '{desc}' {branches}\n"
+  > EOF
+
+
+  $ hg init a
+  $ cd a
+
+  $ echo A > A
+  $ hg ci -Am A
+  adding A
+
+  $ echo B > B
+  $ hg ci -Am B
+  adding B
+
+  $ hg up -q -C 0
+
+  $ echo C > C
+  $ hg ci -Am C
+  adding C
+  created new head
+
+  $ hg up -q -C 0
+
+  $ echo D > D
+  $ hg ci -Am D
+  adding D
+  created new head
+
+  $ hg merge -r 2
+  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
+  (branch merge, don't forget to commit)
+
+  $ hg ci -m E
+
+  $ hg up -q -C 3
+
+  $ echo F > F
+  $ hg ci -Am F
+  adding F
+  created new head
+
+  $ cd ..
+
+
+Rebasing descendant onto ancestor across different named branches
+
+  $ hg clone -q -u . a a1
+
+  $ cd a1
+
+  $ hg branch dev
+  marked working directory as branch dev
+
+  $ echo x > x
+
+  $ hg add x
+
+  $ hg ci -m 'extra named branch'
+
+  $ hg tglog
+  @  6: 'extra named branch' dev
+  |
+  o  5: 'F'
+  |
+  | o  4: 'E'
+  |/|
+  o |  3: 'D'
+  | |
+  | o  2: 'C'
+  |/
+  | o  1: 'B'
+  |/
+  o  0: 'A'
+  
+  $ hg rebase -s 6 -d 5
+  saved backup bundle to $TESTTMP/a1/.hg/strip-backup/*-backup.hg (glob)
+
+  $ hg tglog
+  @  6: 'extra named branch'
+  |
+  o  5: 'F'
+  |
+  | o  4: 'E'
+  |/|
+  o |  3: 'D'
+  | |
+  | o  2: 'C'
+  |/
+  | o  1: 'B'
+  |/
+  o  0: 'A'
+  
+  $ cd ..
+ 
+Rebasing descendant onto ancestor across the same named branches
+
+  $ hg clone -q -u . a a2
+
+  $ cd a2
+
+  $ echo x > x
+
+  $ hg add x
+
+  $ hg ci -m 'G'
+
+  $ hg tglog
+  @  6: 'G'
+  |
+  o  5: 'F'
+  |
+  | o  4: 'E'
+  |/|
+  o |  3: 'D'
+  | |
+  | o  2: 'C'
+  |/
+  | o  1: 'B'
+  |/
+  o  0: 'A'
+  
+  $ hg rebase -s 6 -d 5
+  abort: source is descendant of destination
+  [255]
+
+  $ cd ..
+ 
+Rebasing ancestor onto descendant across different named branches
+
+  $ hg clone -q -u . a a3
+
+  $ cd a3
+
+  $ hg branch dev
+  marked working directory as branch dev
+
+  $ echo x > x
+
+  $ hg add x
+
+  $ hg ci -m 'extra named branch'
+
+  $ hg tglog
+  @  6: 'extra named branch' dev
+  |
+  o  5: 'F'
+  |
+  | o  4: 'E'
+  |/|
+  o |  3: 'D'
+  | |
+  | o  2: 'C'
+  |/
+  | o  1: 'B'
+  |/
+  o  0: 'A'
+  
+  $ hg rebase -s 5 -d 6
+  abort: source is ancestor of destination
+  [255]
+
+  $ cd ..
+ 
+