diff --git a/openvswitch/tests/ovs_basic.py b/openvswitch/tests/ovs_basic.py
index e39b5817e9e2ab31888de0334963f352ed256f51..82d0f59fc8ac1d25c67ace9774aa668420ec3616 100644
--- a/openvswitch/tests/ovs_basic.py
+++ b/openvswitch/tests/ovs_basic.py
@@ -75,7 +75,7 @@ class InfrastructureInit(MiniSubtest):
     def clean(self, test, params, env):
         if self.ovs:
             try:
-                if not self.dns_pidf is None:
+                if self.dns_pidf is not None:
                     utils_misc.signal_program(self.dns_pidf[0:-4],
                                               pid_files_dir=test.tmpdir)
             except:
diff --git a/qemu/tests/cpuflags.py b/qemu/tests/cpuflags.py
index a26302c1a6ebc252a00855ae68f8f1817d4cd054..4bac2244f893042457136b64281987e1eb567710 100644
--- a/qemu/tests/cpuflags.py
+++ b/qemu/tests/cpuflags.py
@@ -161,7 +161,7 @@ def run(test, params, env):
                     self.last_model += self.last_arch[attrs['name']]
                     self.sub_model = True
             elif name == "feature":
-                if not self.last_model is None:
+                if self.last_model is not None:
                     self.last_model.append(attrs['name'])
                 else:
                     self.all_flags.append(attrs['name'])
diff --git a/qemu/tests/softlockup.py b/qemu/tests/softlockup.py
index 7e7d2c2acb8378ce702e8cc95615a5260e01aacd..e5abd01e36ae15bc3bebe60f642ae4e6c05fafca 100644
--- a/qemu/tests/softlockup.py
+++ b/qemu/tests/softlockup.py
@@ -70,7 +70,7 @@ def run(test, params, env):
         utils.run(server_setup_cmd % (monitor_dir, threshold,
                                       monitor_log_file_server, monitor_port))
 
-        if not stress_setup_cmd is None:
+        if stress_setup_cmd is not None:
             logging.info("Build stress on host")
             # Uncompress and build stress on host
             utils.run(stress_setup_cmd % stress_dir)
@@ -121,7 +121,7 @@ def run(test, params, env):
         session.cmd(params.get("client_setup_cmd") %
                     ("/tmp", host_ip, monitor_log_file_client, monitor_port))
 
-        if not stress_setup_cmd is None:
+        if stress_setup_cmd is not None:
             # Copy, uncompress and build stress on guest
             stress_source = params.get("stress_source")
             stress_path = os.path.join(stress_dir, stress_source)