diff --git a/pyexcel_xls/xlsr.py b/pyexcel_xls/xlsr.py
index 999c023..8e679c7 100644
--- a/pyexcel_xls/xlsr.py
+++ b/pyexcel_xls/xlsr.py
@@ -152,9 +152,7 @@ class XLSReader(IReader):
     def read_sheet(self, index):
         native_sheet = self.content_array[index]
         sheet = XLSheet(
-            native_sheet,
-            date_mode=self.xls_book.datemode,
-            **self._keywords
+            native_sheet, date_mode=self.xls_book.datemode, **self._keywords
         )
         return sheet
 
diff --git a/tests/test_formatters.py b/tests/test_formatters.py
index 0dcd74a..e87a017 100644
--- a/tests/test_formatters.py
+++ b/tests/test_formatters.py
@@ -37,6 +37,15 @@ class TestDateFormat:
                 datetime.date(2014, 12, 25),
                 datetime.time(11, 11, 11),
                 datetime.datetime(2014, 12, 25, 11, 11, 11),
+                datetime.timedelta(
+                        days=50,
+                        seconds=27,
+                        microseconds=10,
+                        milliseconds=29000,
+                        minutes=5,
+                        hours=8,
+                        weeks=2,
+                ),
             ]
         ]
         pe.save_as(dest_file_name=excel_filename, array=data)
@@ -47,6 +56,8 @@ class TestDateFormat:
         assert r[0, 1].strftime("%H:%M:%S") == "11:11:11"
         assert isinstance(r[0, 2], datetime.date) is True
         assert r[0, 2].strftime("%d/%m/%y %H:%M:%S") == "25/12/14 11:11:11"
+        assert isinstance(r[0, 2], datetime.timedelta)
+        assert r[0, 1].strftime("%H:%M:%S") == "3:30:20"
         os.unlink(excel_filename)