diff --git a/mercurial/subrepo.py b/mercurial/subrepo.py
--- a/mercurial/subrepo.py
+++ b/mercurial/subrepo.py
@@ -1530,10 +1530,17 @@ class gitsubrepo(abstractsubrepo):
         (modified, added, removed,
          deleted, unknown, ignored, clean) = self.status(None)
 
+        tracked = set()
+        # dirstates 'amn' warn, 'r' is added again
+        for l in (modified, added, deleted, clean):
+            tracked.update(l)
+
         # Unknown files not of interest will be rejected by the matcher
         files = unknown
         files.extend(match.files())
 
+        rejected = []
+
         files = [f for f in sorted(set(files)) if match(f)]
         for f in files:
             exact = match.exact(f)
@@ -1542,9 +1549,18 @@ class gitsubrepo(abstractsubrepo):
                 command.append("-f") #should be added, even if ignored
             if ui.verbose or not exact:
                 ui.status(_('adding %s\n') % match.rel(f))
+
+            if f in tracked:  # hg prints 'adding' even if already tracked
+                if exact:
+                    rejected.append(f)
+                continue
             if not opts.get('dry_run'):
                 self._gitcommand(command + [f])
-        return []
+
+        for f in rejected:
+            ui.warn(_("%s already tracked!\n") % match.abs(f))
+
+        return rejected
 
     @annotatesubrepoerror
     def remove(self):
diff --git a/tests/test-subrepo-git.t b/tests/test-subrepo-git.t
--- a/tests/test-subrepo-git.t
+++ b/tests/test-subrepo-git.t
@@ -974,7 +974,26 @@ correctly do a dry run
   ? s/cpp.cpp
   ? s/foobar.orig
 
-currently no error given when adding an already tracked file
+error given when adding an already tracked file
   $ hg add s/.gitignore
+  s/.gitignore already tracked!
+  [1]
+
+removed files can be re-added
+  $ hg ci --subrepos -m 'snake'
+  committing subrepository s
+  $ cd s
+  $ git rm snake.python
+  rm 'snake.python'
+  $ touch snake.python
+  $ cd ..
+  $ hg add s/snake.python
+  $ hg status -S
+  M s/snake.python
+  ? .hgignore
+  ? s/barfoo
+  ? s/c.c
+  ? s/cpp.cpp
+  ? s/foobar.orig
 
   $ cd ..