diff --git a/marconi/storage/exceptions.py b/marconi/storage/exceptions.py
index 99f27c9a7..cf18e2591 100644
--- a/marconi/storage/exceptions.py
+++ b/marconi/storage/exceptions.py
@@ -84,6 +84,13 @@ class MessageDoesNotExist(DoesNotExist):
         super(MessageDoesNotExist, self).__init__(msg)
 
 
+class MessageIsClaimed(NotPermitted):
+
+    def __init__(self, mid):
+        msg = (u'Message %(mid)s is claimed' % dict(mid=mid))
+        super(MessageIsClaimed, self).__init__(msg)
+
+
 class ClaimDoesNotExist(DoesNotExist):
 
     def __init__(self, cid, queue, project):
@@ -93,9 +100,9 @@ class ClaimDoesNotExist(DoesNotExist):
         super(ClaimDoesNotExist, self).__init__(msg)
 
 
-class ClaimNotPermitted(NotPermitted):
+class MessageIsClaimedBy(NotPermitted):
 
     def __init__(self, mid, cid):
         msg = (u'Message %(mid)s is not claimed by %(cid)s' %
                dict(cid=cid, mid=mid))
-        super(ClaimNotPermitted, self).__init__(msg)
+        super(MessageIsClaimedBy, self).__init__(msg)
diff --git a/marconi/storage/mongodb/messages.py b/marconi/storage/mongodb/messages.py
index c0aafca2b..b85dfb82c 100644
--- a/marconi/storage/mongodb/messages.py
+++ b/marconi/storage/mongodb/messages.py
@@ -609,29 +609,32 @@ class MessageController(storage.MessageBase):
             '_id': mid
         }
 
-        if claim:
-            # NOTE(cpp-cabrera): return early - the user gaves us an
-            # invalid claim id and that renders the rest of this
-            # request moot
-            cid = utils.to_oid(claim)
-            if cid is None:
-                return
+        # NOTE(cpp-cabrera): return early - the user gaves us an
+        # invalid claim id and that renders the rest of this
+        # request moot
+        cid = utils.to_oid(claim)
+        if cid is None:
+            return
 
-            now = timeutils.utcnow()
-            query['e'] = {'$gt': now}
-            message = self._col.find_one(query)
+        now = timeutils.utcnow()
+        query['e'] = {'$gt': now}
+        message = self._col.find_one(query)
 
-            if message is None:
-                return None
+        if message is None:
+            return
 
-            if not ('c' in message and
-                    message['c']['id'] == cid and
-                    message['c']['e'] > now):
-                raise exceptions.ClaimNotPermitted(message_id, claim)
+        is_claimed = (message['c']['id'] is not None and
+                      message['c']['e'] > now)
+
+        if claim is None:
+            if is_claimed:
+                raise exceptions.MessageIsClaimed(message_id)
 
-            self._col.remove(query['_id'], w=0)
         else:
-            self._col.remove(query, w=0)
+            if message['c']['id'] != cid:
+                raise exceptions.MessageIsClaimedBy(message_id, claim)
+
+        self._col.remove(query['_id'], w=0)
 
     @utils.raises_conn_error
     def bulk_delete(self, queue_name, message_ids, project=None):
diff --git a/marconi/storage/sqlite/messages.py b/marconi/storage/sqlite/messages.py
index 3fea195f8..fc29612cf 100644
--- a/marconi/storage/sqlite/messages.py
+++ b/marconi/storage/sqlite/messages.py
@@ -223,15 +223,6 @@ class MessageController(base.MessageBase):
         if id is None:
             return
 
-        if not claim:
-            self.driver.run('''
-                delete from Messages
-                 where id = ?
-                   and qid = (select id from Queues
-                               where project = ? and name = ?)
-            ''', id, project, queue)
-            return
-
         with self.driver('immediate'):
             message_exists, = self.driver.get('''
                 select count(M.id)
@@ -244,7 +235,23 @@ class MessageController(base.MessageBase):
             if not message_exists:
                 return
 
-            self.__delete_claimed(id, claim)
+            if claim is None:
+                self.__delete_unclaimed(id)
+            else:
+                self.__delete_claimed(id, claim)
+
+    def __delete_unclaimed(self, id):
+        self.driver.run('''
+            delete from Messages
+             where id = ?
+               and not exists (select *
+                                 from Claims join Locked
+                                   on id = cid
+                                where ttl > julianday() * 86400.0 - created)
+        ''', id)
+
+        if not self.driver.affected:
+            raise exceptions.MessageIsClaimed(id)
 
     def __delete_claimed(self, id, claim):
         # Precondition: id exists in a specific queue
@@ -263,7 +270,7 @@ class MessageController(base.MessageBase):
         ''', id, cid)
 
         if not self.driver.affected:
-            raise exceptions.ClaimNotPermitted(id, claim)
+            raise exceptions.MessageIsClaimedBy(id, claim)
 
     def bulk_delete(self, queue, message_ids, project):
         if project is None:
diff --git a/marconi/tests/transport/wsgi/test_claims.py b/marconi/tests/transport/wsgi/test_claims.py
index ecdc64bfa..b11c4ae90 100644
--- a/marconi/tests/transport/wsgi/test_claims.py
+++ b/marconi/tests/transport/wsgi/test_claims.py
@@ -145,6 +145,10 @@ class ClaimsBaseTest(base.TestBase):
                           claim_href)
         self.assertEquals(claim['ttl'], 100)
 
+        # Try to delete the message without submitting a claim_id
+        self.simulate_delete(message_href, self.project_id)
+        self.assertEquals(self.srmock.status, falcon.HTTP_403)
+
         # Delete the message and its associated claim
         self.simulate_delete(message_href, self.project_id,
                              query_string=params)
diff --git a/marconi/transport/wsgi/messages.py b/marconi/transport/wsgi/messages.py
index d3ce444ae..11e713b50 100644
--- a/marconi/transport/wsgi/messages.py
+++ b/marconi/transport/wsgi/messages.py
@@ -290,10 +290,11 @@ class ItemResource(object):
 
         except storage_exceptions.NotPermitted as ex:
             LOG.exception(ex)
-            title = _(u'Invalid claim')
-            description = _(u'The specified claim either does not '
-                            u'exist or has expired.')
+            title = _(u'Unable to delete')
+            description = _(u'This message is claimed; it cannot be '
+                            u'deleted without a valid claim_id.')
             raise falcon.HTTPForbidden(title, description)
+
         except Exception as ex:
             LOG.exception(ex)
             description = _(u'Message could not be deleted.')