diff --git a/tests/test_vm2vm.py b/tests/test_vm2vm.py
index d6a4242..ac6bbc0 100644
--- a/tests/test_vm2vm.py
+++ b/tests/test_vm2vm.py
@@ -110,9 +110,12 @@
                 floating_ip=vm_info[i]['fip'], timeout=ssh_timeout)
         with ThreadPoolExecutor() as executor:
             futures = [
-                executor.submit(ssh.install_iperf_at_vms_and_get_mtu, vm_info)
+                executor.submit(ssh.install_iperf_at_vm, vm_info)
                 for vm_info in vm_info]
-            mtus = [future.result() for future in futures]
+        logger.info("Getting MTUs at VMs...")
+        mtus = []
+        for vm in vm_info:
+            mtus.append(ssh.get_mtu_at_vm(vm))
         logger.info("MTU at networks: {}, {}".format(
             os_resources['net1']['mtu'], os_resources['net2']['mtu']))
         # Prepare the result table and run iperf3
diff --git a/tests/test_vm2vm_different_routers.py b/tests/test_vm2vm_different_routers.py
index 8b38a4b..1fa8850 100644
--- a/tests/test_vm2vm_different_routers.py
+++ b/tests/test_vm2vm_different_routers.py
@@ -127,9 +127,12 @@
                 floating_ip=vm_info[i]['fip'], timeout=ssh_timeout)
         with ThreadPoolExecutor() as executor:
             futures = [
-                executor.submit(ssh.install_iperf_at_vms_and_get_mtu, vm_info)
+                executor.submit(ssh.install_iperf_at_vm, vm_info)
                 for vm_info in vm_info]
-            mtus = [future.result() for future in futures]
+        logger.info("Getting MTUs at VMs...")
+        mtus = []
+        for vm in vm_info:
+            mtus.append(ssh.get_mtu_at_vm(vm))
         logger.info(
             "MTU at networks: {}, {}".format(
                 os_resources['net1']['mtu'],