diff --git a/Lib/test/test_file.py b/Lib/test/test_file.py
index a85e07cacf7..cb1bdce08e0 100644
--- a/Lib/test/test_file.py
+++ b/Lib/test/test_file.py
@@ -46,4 +46,15 @@ else:
     print "writelines accepted sequence of non-string objects"
 f.close()
 
+# verify that we get a sensible error message for bad made argument
+bad_mode = "qwerty"
+try:
+    open(TESTFN, bad_mode)
+except IOError, msg:
+    s = str(msg)
+    if s.find(TESTFN) != -1 or s.find(bad_mode) == -1:
+        print "bad error message for invalid mode: %s" % s
+else:
+    print "no error for invalid mode: %s" % bad_mode
+
 os.unlink(TESTFN)
diff --git a/Objects/fileobject.c b/Objects/fileobject.c
index ebccc845cc2..9284185be63 100644
--- a/Objects/fileobject.c
+++ b/Objects/fileobject.c
@@ -121,13 +121,17 @@ open_the_file(PyFileObject *f, char *name, char *mode)
 	if (f->f_fp == NULL) {
 #ifdef NO_FOPEN_ERRNO
 		/* Metroworks only, not testable, so unchanged */
-		if ( errno == 0 ) {
+		if (errno == 0) {
 			PyErr_SetString(PyExc_IOError, "Cannot open file");
 			Py_DECREF(f);
 			return NULL;
 		}
 #endif
-		PyErr_SetFromErrnoWithFilename(PyExc_IOError, name);
+		if (errno == EINVAL)
+			PyErr_Format(PyExc_IOError, "invalid argument: %s",
+				     mode);
+		else
+			PyErr_SetFromErrnoWithFilename(PyExc_IOError, name);
 		f = NULL;
 	}
 	return (PyObject *)f;