diff --git a/orlo/queries.py b/orlo/queries.py
index 30d4261..aefc517 100644
--- a/orlo/queries.py
+++ b/orlo/queries.py
@@ -183,13 +183,17 @@ def releases(**kwargs):
     if any(field.startswith('package_') for field in kwargs.keys()) \
             or "status" in kwargs.keys():
         # Package attributes need the join, as does status as it's really a
-        # package
-        # attribute
+        # package attribute
         query = db.session.query(Release).join(Package)
     else:
         # No need to join on package if none of our params need it
         query = db.session.query(Release)
 
+    for key in kwargs.keys():
+        if isinstance(kwargs[key], bool):
+            continue
+        if kwargs[key].lower() in ['null', 'none']:
+            kwargs[key] = None
     try:
         query = apply_filters(query, kwargs)
     except AttributeError as e:
diff --git a/tests/test_contract.py b/tests/test_contract.py
index 1950b94..a4bb4ba 100644
--- a/tests/test_contract.py
+++ b/tests/test_contract.py
@@ -487,8 +487,12 @@ def _get_releases_time_filter(self, field, finished=False):
         yesterday = (now - timedelta(days=1)).strftime(t_format)
         tomorrow = (now + timedelta(days=1)).strftime(t_format)
 
-        r_yesterday = self._get_releases(filters=['{}={}'.format(field, yesterday)])
-        r_tomorrow = self._get_releases(filters=['{}={}'.format(field, tomorrow)])
+        r_yesterday = self._get_releases(
+            filters=['{}={}'.format(field, yesterday)]
+        )
+        r_tomorrow = self._get_releases(
+            filters=['{}={}'.format(field, tomorrow)]
+        )
 
         return r_yesterday, r_tomorrow
 
@@ -501,6 +505,15 @@ def test_get_release_filter_stime_before(self):
         self.assertEqual(3, len(r_tomorrow['releases']))
         self.assertEqual(0, len(r_yesterday['releases']))
 
+    def test_get_release_filter_ftime_null(self):
+        """
+        Filter on releases that don't have a finish time
+        """
+        releases = self._get_releases(
+            filters=['{}={}'.format('ftime', 'null')]
+        )
+        self.assertEqual(len(releases['releases']), 0)
+
     def test_get_release_filter_stime_after(self):
         """
         Filter on releases that started after a particular time