diff --git a/tangostationcontrol/test/devices/sdp/test_beamlet_device.py b/tangostationcontrol/test/devices/sdp/test_beamlet_device.py
index f8b1c74ed9180168e0c7f4bbafba870931f6cb02..062113ed123d3e044a0bb115a6824d233d89b43d 100644
--- a/tangostationcontrol/test/devices/sdp/test_beamlet_device.py
+++ b/tangostationcontrol/test/devices/sdp/test_beamlet_device.py
@@ -135,11 +135,11 @@ class TestBeamletDevice(base.TestCase):
 
         self.assertListEqual(
             defaults["FPGA_beamlet_output_multiple_hdr_eth_destination_mac_RW"],
-            [MACs + [""] * (N_bdo_destinations_mm - 4)] * N_pn,
+            [MACs + ["00:00:00:00:00:00"] * (N_bdo_destinations_mm - 4)] * N_pn,
         )
         self.assertListEqual(
             defaults["FPGA_beamlet_output_multiple_hdr_ip_destination_address_RW"],
-            [IPs + [""] * (N_bdo_destinations_mm - 4)] * N_pn,
+            [IPs + ["0.0.0.0"] * (N_bdo_destinations_mm - 4)] * N_pn,
         )
         self.assertListEqual(
             defaults["FPGA_beamlet_output_multiple_hdr_udp_destination_port_RW"],