diff --git a/tests/scripts/thread-cert/border_router/test_multi_thread_networks.py b/tests/scripts/thread-cert/border_router/test_multi_thread_networks.py
index 4e0823b0a..eaa1e13a0 100755
--- a/tests/scripts/thread-cert/border_router/test_multi_thread_networks.py
+++ b/tests/scripts/thread-cert/border_router/test_multi_thread_networks.py
@@ -130,17 +130,10 @@ class MultiThreadNetworks(thread_cert.TestCase):
 
         # Each BR should independently register an external route for the on-link prefix
         # and OMR prefix in another Thread Network.
-        self.assertTrue(len(br1.get_netdata_non_nat64_prefixes()) == 1)
-        self.assertTrue(len(router1.get_netdata_non_nat64_prefixes()) == 1)
-        self.assertTrue(len(br2.get_netdata_non_nat64_prefixes()) == 1)
-        self.assertTrue(len(router2.get_netdata_non_nat64_prefixes()) == 1)
-
-        br1_external_routes = br1.get_routes()
-        br2_external_routes = br2.get_routes()
-
-        br1_external_routes.sort()
-        br2_external_routes.sort()
-        self.assertNotEqual(br1_external_routes, br2_external_routes)
+        self.assertEqual(br1.get_netdata_non_nat64_prefixes(), ['fc00::/7'])
+        self.assertEqual(router1.get_netdata_non_nat64_prefixes(), ['fc00::/7'])
+        self.assertEqual(br2.get_netdata_non_nat64_prefixes(), ['fc00::/7'])
+        self.assertEqual(router2.get_netdata_non_nat64_prefixes(), ['fc00::/7'])
 
         self.assertTrue(len(router1.get_ip6_address(config.ADDRESS_TYPE.OMR)) == 1)
         self.assertTrue(len(router2.get_ip6_address(config.ADDRESS_TYPE.OMR)) == 1)