diff --git a/tangostationcontrol/tangostationcontrol/test/beam/test_delays.py b/tangostationcontrol/tangostationcontrol/test/beam/test_delays.py
index 264badb877e0cc21c6f47862bf87138452b04ba1..82b4c2b9aeaf03f330fd5736517a59db9ee41e3b 100644
--- a/tangostationcontrol/tangostationcontrol/test/beam/test_delays.py
+++ b/tangostationcontrol/tangostationcontrol/test/beam/test_delays.py
@@ -78,6 +78,7 @@ class TestDelays(base.TestCase):
         This test measures whether the distance between 2 positions is 0.1 light second apart.
         """
 
+        reference_itrf = [0, 0, 0]
         d = delay_calculator(reference_itrf)
 
         # set the antenna position 0.1 lightsecond in the Z direction of the ITRF,