diff --git a/src/p4p/test/test_gw.py b/src/p4p/test/test_gw.py
index f740fc5..bf04f9d 100644
--- a/src/p4p/test/test_gw.py
+++ b/src/p4p/test/test_gw.py
@@ -225,7 +225,7 @@ def test_monitor(self):
         Q2 = Queue(maxsize=4)
 
         with self._ds_client.monitor('pv:ro', Q1.put, notify_disconnect=True):
-            
+
             self.assertIsInstance(Q1.get(timeout=self.timeout), Disconnected)
             self.assertEqual(42, Q1.get(timeout=self.timeout))
 
@@ -296,7 +296,7 @@ def put(pv, op):
         _log.debug("Exit setUp")
 
     def setUpGW(self, usconfig):
-        cfile = self._cfile = NamedTemporaryFile('w+')
+        cfile = self._cfile = NamedTemporaryFile(mode='w+')
         json.dump({
             'version':2,
             'clients':[{
@@ -474,7 +474,7 @@ class TestHighLevelChained(TestHighLevel):
 
     def setUpGW(self, usconfig):
         # First GW, connected to upstream server
-        cfile = self._cfile = NamedTemporaryFile('w+')
+        cfile = self._cfile = NamedTemporaryFile(mode='w+')
         json.dump({
             'version':2,
             'clients':[{
@@ -510,7 +510,7 @@ def setUpGW(self, usconfig):
         gw1config = self._app1.servers[u'server1_0'].conf()
 
         # Second GW, connected to first
-        cfile = self._cfile = NamedTemporaryFile('w+')
+        cfile = self._cfile = NamedTemporaryFile(mode='w+')
         json.dump({
             'version':2,
             'clients':[{
@@ -635,7 +635,7 @@ def log(self):
         return self._log.read()
 
     def write(self, content):
-        F = NamedTemporaryFile('w+')
+        F = NamedTemporaryFile(mode='w+')
         self._files.append(F)
         F.write(content)
         F.flush()
diff --git a/src/p4p/test/utils.py b/src/p4p/test/utils.py
index 4b8d150..7886ec2 100644
--- a/src/p4p/test/utils.py
+++ b/src/p4p/test/utils.py
@@ -170,9 +170,14 @@ class RegularNamedTemporaryFile(object):
     """Like tempfile.NamedTemporaryFile which doesn't use O_TEMPORARY on windows
     """
     def __init__(self, *args, **kws):
-        fd, self.name = tempfile.mkstemp(**kws)
+        mkstemp_kws = {k: v for k, v in kws.items()
+                       if k in ['suffix', 'prefix', 'dir']}
+        fd, self.name = tempfile.mkstemp(**mkstemp_kws)
         try:
-            self.file = os.fdopen(fd, *args, **kws)
+            if 'mode' in kws:
+                self.file = os.fdopen(fd, kws['mode'])
+            else:
+                self.file = os.fdopen(fd)
             self.read = self.file.read
             self.write = self.file.write
             self.flush = self.file.flush