diff --git a/lib/iris/tests/unit/coord_categorisation/test_add_categorised_coord.py b/lib/iris/tests/unit/coord_categorisation/test_add_categorised_coord.py
index 170a92cc6dc..0d2ee8046e3 100644
--- a/lib/iris/tests/unit/coord_categorisation/test_add_categorised_coord.py
+++ b/lib/iris/tests/unit/coord_categorisation/test_add_categorised_coord.py
@@ -99,6 +99,8 @@ def setUp(self):
             'proleptic_gregorian': np.array(list(range(360, 367)) +
                                             list(range(1, 4))),
             'noleap': np.array(list(range(359, 366)) + list(range(1, 4))),
+
+            'julian': np.array(list(range(360, 367)) + list(range(1, 4))),
             'all_leap': np.array(list(range(360, 367)) + list(range(1, 4))),
             '365_day': np.array(list(range(359, 366)) + list(range(1, 4))),
             '366_day': np.array(list(range(360, 367)) + list(range(1, 4))),
@@ -114,7 +116,12 @@ def make_cube(self, calendar):
         return cube
 
     def test_calendars(self):
-        for calendar in self.expected:
+        for calendar in calendars:
+            # Skip the Julian calendar due to
+            # https://github.com/Unidata/netcdftime/issues/13
+            # Remove this if block once the issue is resolved.
+            if calendar == 'julian':
+                continue
             cube = self.make_cube(calendar)
             add_day_of_year(cube, 'time')
             points = cube.coord('day_of_year').points