diff --git a/tests/scripts/thread-cert/Cert_5_1_05_RouterAddressTimeout.py b/tests/scripts/thread-cert/Cert_5_1_05_RouterAddressTimeout.py
index ddf4adc62..cce38a959 100755
--- a/tests/scripts/thread-cert/Cert_5_1_05_RouterAddressTimeout.py
+++ b/tests/scripts/thread-cert/Cert_5_1_05_RouterAddressTimeout.py
@@ -83,7 +83,7 @@ class Cert_5_1_05_RouterAddressTimeout(unittest.TestCase):
         self._setUpRouter1()
         self.simulator.go(200)
         self.nodes[ROUTER1].start()
-        self.simulator.go(5)
+        self.simulator.go(15)
         self.assertEqual(self.nodes[ROUTER1].get_state(), 'router')
         self.assertNotEqual(self.nodes[ROUTER1].get_addr16(), rloc16)
 
@@ -92,7 +92,7 @@ class Cert_5_1_05_RouterAddressTimeout(unittest.TestCase):
         self._setUpRouter1()
         self.simulator.go(300)
         self.nodes[ROUTER1].start()
-        self.simulator.go(5)
+        self.simulator.go(15)
         self.assertEqual(self.nodes[ROUTER1].get_state(), 'router')
         self.assertEqual(self.nodes[ROUTER1].get_addr16(), rloc16)
 
diff --git a/tests/scripts/thread-cert/Cert_5_6_01_NetworkDataRegisterBeforeAttachLeader.py b/tests/scripts/thread-cert/Cert_5_6_01_NetworkDataRegisterBeforeAttachLeader.py
index 66ac8a508..06bf9b534 100755
--- a/tests/scripts/thread-cert/Cert_5_6_01_NetworkDataRegisterBeforeAttachLeader.py
+++ b/tests/scripts/thread-cert/Cert_5_6_01_NetworkDataRegisterBeforeAttachLeader.py
@@ -86,6 +86,7 @@ class Cert_5_6_1_NetworkDataLeaderAsBr(unittest.TestCase):
         self.nodes[LEADER].add_prefix('2001:2:0:1::/64', 'paros')
         self.nodes[LEADER].add_prefix('2001:2:0:2::/64', 'paro')
         self.nodes[LEADER].register_netdata()
+        self.simulator.go(5)
 
         self.nodes[ROUTER].start()
         self.simulator.go(5)
diff --git a/tests/scripts/thread-cert/Cert_6_3_02_NetworkDataUpdate.py b/tests/scripts/thread-cert/Cert_6_3_02_NetworkDataUpdate.py
index de9b6906e..8bfb35a96 100755
--- a/tests/scripts/thread-cert/Cert_6_3_02_NetworkDataUpdate.py
+++ b/tests/scripts/thread-cert/Cert_6_3_02_NetworkDataUpdate.py
@@ -36,7 +36,7 @@ import node
 LEADER = 1
 ED = 2
 
-class Cert_5_6_2_NetworkDataUpdate(unittest.TestCase):
+class Cert_6_3_2_NetworkDataUpdate(unittest.TestCase):
     def setUp(self):
         self.simulator = config.create_default_simulator()
 
@@ -75,6 +75,7 @@ class Cert_5_6_2_NetworkDataUpdate(unittest.TestCase):
         self.simulator.go(5)
 
         addrs = self.nodes[ED].get_addrs()
+        self.simulator.go(5)
         self.assertTrue(any('2001:2:0:1' in addr[0:10] for addr in addrs))
         for addr in addrs:
             if addr[0:10] == '2001:2:0:1':