diff --git a/swh/loader/git/tests/test_date.py b/swh/loader/git/tests/test_date.py
index 8289fc5..b4b9e25 100644
--- a/swh/loader/git/tests/test_date.py
+++ b/swh/loader/git/tests/test_date.py
@@ -1,29 +1,56 @@
 # Copyright (C) 2015  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
 import unittest
 
 from nose.tools import istest
 
 from swh.loader.git import date
 
 
 class DateTestCase(unittest.TestCase):
     @istest
-    def new_swhrepo(self):
+    def negative_offsets(self):
+        # when
+        d0 = date.ts_to_datetime(1434379797, -120)
+
+        assert str(d0) == '2015-06-15 12:49:57-02:00'
+
+        # when
+        d1 = date.ts_to_datetime(1434379797, -60)
+
+        assert str(d1) == '2015-06-15 13:49:57-01:00'
+
+        # when
+        d2 = date.ts_to_datetime(1434379797, -30)
+
+        assert str(d2) == '2015-06-15 14:19:57-00:30'
+
+        # when
+        d3 = date.ts_to_datetime(1434379797, 30)
+
+        assert str(d3) == '2015-06-15 15:19:57+00:30'
+
+    @istest
+    def positive_offsets(self):
         # when
         d0 = date.ts_to_datetime(1434449254, 120)
 
         assert str(d0) == '2015-06-16 12:07:34+02:00'
 
         # when
         d1 = date.ts_to_datetime(1434449254, 60)
 
         assert str(d1) == '2015-06-16 11:07:34+01:00'
 
         # when
         d2 = date.ts_to_datetime(1434449254, 0)
 
         assert str(d2) == '2015-06-16 10:07:34+00:00'
+
+        # when
+        d3 = date.ts_to_datetime(1434449254, -60)
+
+        assert str(d3) == '2015-06-16 09:07:34-01:00'