diff -r 416cd57d38cf Lib/test/test_os.py
--- a/Lib/test/test_os.py	Sun Jul 15 00:38:43 2012 +1000
+++ b/Lib/test/test_os.py	Tue Jul 17 18:19:05 2012 -0500
@@ -355,6 +355,13 @@
                                 os.utime in os.supports_follow_symlinks,
                                 "follow_symlinks support for utime required for this test.")
 
+    def test_utime_ns_none(self):
+        # Issue 15382 - ns=None ought to be given explicitly without error
+        os.utime(self.fname, ns=None)
+        os.utime(self.fname, times=None, ns=None)
+        os.utime(self.fname, times=(1000, 1000), ns=None)
+
+
     @requires_utime_nofollow_symlinks
     def test_lutimes_ns(self):
         def lutimes_ns(file, times):
diff -r 416cd57d38cf Modules/posixmodule.c
--- a/Modules/posixmodule.c	Sun Jul 15 00:38:43 2012 +1000
+++ b/Modules/posixmodule.c	Tue Jul 17 18:19:05 2012 -0500
@@ -4617,7 +4617,7 @@
             ))
         return NULL;
 
-    if (times && (times != Py_None) && ns) {
+    if (times && (times != Py_None) && ns && (ns != Py_None)) {
         PyErr_SetString(PyExc_ValueError,
                      "utime: you may specify either 'times'"
                      " or 'ns' but not both");
@@ -4639,7 +4639,7 @@
             goto exit;
         }
     }
-    else if (ns) {
+    else if (ns && (ns != Py_None)) {
         if (!PyTuple_CheckExact(ns) || (PyTuple_Size(ns) != 2)) {
             PyErr_SetString(PyExc_TypeError,
                          "utime: 'ns' must be a tuple of two ints");