diff --git a/test/test-network/conf/25-route-congctl.network b/test/test-network/conf/25-route-congctl.network
index f924d73cd9..2af783ad14 100644
--- a/test/test-network/conf/25-route-congctl.network
+++ b/test/test-network/conf/25-route-congctl.network
@@ -10,7 +10,9 @@ Address=149.10.124.58/28
 [Route]
 Destination=2001:1234:5:8fff:ff:ff:ff:ff/128
 TCPCongestionControlAlgorithm=dctcp
+TCPRetransmissionTimeOutSec=300s
 
 [Route]
 Destination=149.10.124.66
 TCPCongestionControlAlgorithm=dctcp
+TCPRetransmissionTimeOutSec=300s
diff --git a/test/test-network/systemd-networkd-tests.py b/test/test-network/systemd-networkd-tests.py
index 07afe354f7..cc10bdfc96 100755
--- a/test/test-network/systemd-networkd-tests.py
+++ b/test/test-network/systemd-networkd-tests.py
@@ -3175,6 +3175,7 @@ class NetworkdNetworkTests(unittest.TestCase, Utilities):
         print(output)
         self.assertIn('149.10.124.66 proto static', output)
         self.assertIn('congctl dctcp', output)
+        self.assertIn('rto_min 300s', output)
 
     @expectedFailureIfModuleIsNotAvailable('vrf')
     def test_route_vrf(self):