diff --git a/pubs/commands/add_cmd.py b/pubs/commands/add_cmd.py
index a8461e6..1dc5907 100644
--- a/pubs/commands/add_cmd.py
+++ b/pubs/commands/add_cmd.py
@@ -81,8 +81,9 @@ def command(args):
     if citekey is None:
         base_key = bibstruct.extract_citekey(bibdata)
         citekey = rp.unique_citekey(base_key)
-    else:
-        rp.databroker.exists(citekey, meta_check=False)
+    elif citekey in rp:
+        ui.error('citekey already exist {}.'.format(citekey))
+        ui.exit(1)
 
     p = paper.Paper(bibdata, citekey=citekey)
 
diff --git a/pubs/repo.py b/pubs/repo.py
index 4ea1f0f..2873f51 100644
--- a/pubs/repo.py
+++ b/pubs/repo.py
@@ -36,9 +36,10 @@ class Repository(object):
     def __contains__(self, citekey):
         """ Allows to use 'if citekey in repo' pattern
 
-            Warning: costly the first time.
+        The convention is that the paper is in the repository
+        if and only if a bibfile is in the repository.
         """
-        return citekey in self.citekeys
+        return self.databroker.exists(citekey)
 
     def __len__(self):
         """Warning: costly the first time."""
@@ -51,8 +52,7 @@ class Repository(object):
 
     def pull_paper(self, citekey):
         """Load a paper by its citekey from disk, if necessary."""
-        if self.databroker.exists(citekey, meta_check=True):
-            #TODO meta_check=False and default meta generation
+        if citekey in self:
             return Paper(self.databroker.pull_bibdata(citekey),
                          citekey=citekey,
                          metadata=self.databroker.pull_metadata(citekey))
@@ -66,8 +66,7 @@ class Repository(object):
                                if True, mimick the behavior of updating a paper
         """
         bibstruct.check_citekey(paper.citekey)
-        if (not overwrite) and (self.databroker.exists(paper.citekey, meta_check=False)
-                                or (paper.citekey in self)):
+        if (not overwrite) and (paper.citekey in self):
             raise CiteKeyCollision('citekey {} already in use'.format(paper.citekey))
         if not paper.added:
             paper.added = datetime.now()
diff --git a/tests/test_usecase.py b/tests/test_usecase.py
index b45e109..e5ce87a 100644
--- a/tests/test_usecase.py
+++ b/tests/test_usecase.py
@@ -151,6 +151,14 @@ class TestAdd(DataCommandTestCase):
         self.execute_cmds(cmds)
         self.assertEqual(set(self.fs['os'].listdir('/not_default/doc')), {'Page99.pdf'})
 
+    def test_add_citekey(self):
+        cmds = ['pubs init',
+                'pubs add -k CustomCitekey /data/pagerank.bib',
+                ]
+        self.execute_cmds(cmds)
+        bib_dir = self.fs['os'].path.join(self.default_pubs_dir, 'bib')
+        self.assertEqual(set(self.fs['os'].listdir(bib_dir)), {'CustomCitekey.bib'})
+
     def test_add_doc_nocopy_does_not_copy(self):
         cmds = ['pubs init',
                 'pubs add /data/pagerank.bib -C -d /data/pagerank.pdf',
@@ -160,6 +168,14 @@ class TestAdd(DataCommandTestCase):
                 self.fs['os'].path.join(self.default_pubs_dir, 'doc')),
             [])
 
+    def test_add_twice_fails(self):
+        cmds = ['pubs init',
+                'pubs add /data/pagerank.bib',
+                'pubs add -k Page99 /data/turing1950.bib',
+                ]
+        with self.assertRaises(SystemExit):
+            self.execute_cmds(cmds)
+
 
 class TestList(DataCommandTestCase):