diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -2518,6 +2518,39 @@
 
     Py_RETURN_NONE;
 }
+ 
+static PyObject *
+test_pep3118_obsolete_write_locks(PyObject* self, PyObject *noargs)
+{
+    PyObject *b;
+    char *dummy[1];
+    int ret, match;
+
+    ret = PyBuffer_FillInfo(NULL, NULL, dummy, 1, 0, PyBUF_SIMPLE);
+    match = PyErr_Occurred() && PyErr_ExceptionMatches(PyExc_BufferError);
+    PyErr_Clear();
+    if (ret != -1 || match == 0)
+        goto error;
+
+    b = PyByteArray_FromStringAndSize("", 0);
+    if (b == NULL) {
+        return NULL;
+    }
+
+    ret = PyObject_GetBuffer(b, NULL, PyBUF_SIMPLE);
+    Py_DECREF(b);
+    match = PyErr_Occurred() && PyErr_ExceptionMatches(PyExc_BufferError);
+    PyErr_Clear();
+    if (ret != -1 || match == 0)
+        goto error;
+
+    Py_RETURN_NONE;
+
+error:
+    PyErr_SetString(TestError,
+        "test_pep3118_obsolete_write_locks: failure");
+    return NULL;
+}
 
 /* Test that the fatal error from not having a current thread doesn't
    cause an infinite loop.  Run via Lib/test/test_capi.py */
@@ -3179,6 +3212,7 @@
     {"test_unicode_compare_with_ascii", (PyCFunction)test_unicode_compare_with_ascii, METH_NOARGS},
     {"test_capsule", (PyCFunction)test_capsule, METH_NOARGS},
     {"test_from_contiguous", (PyCFunction)test_from_contiguous, METH_NOARGS},
+    {"test_pep3118_obsolete_write_locks", (PyCFunction)test_pep3118_obsolete_write_locks, METH_NOARGS},
     {"getargs_tuple",           getargs_tuple,                   METH_VARARGS},
     {"getargs_keywords", (PyCFunction)getargs_keywords,
       METH_VARARGS|METH_KEYWORDS},
diff --git a/Objects/abstract.c b/Objects/abstract.c
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -612,7 +612,12 @@
 PyBuffer_FillInfo(Py_buffer *view, PyObject *obj, void *buf, Py_ssize_t len,
                   int readonly, int flags)
 {
-    if (view == NULL) return 0; /* XXX why not -1? */
+    if (view == NULL) {
+        PyErr_SetString(PyExc_BufferError,
+            "PyBuffer_FillInfo: view==NULL argument is obsolete");
+        return -1;
+    }
+
     if (((flags & PyBUF_WRITABLE) == PyBUF_WRITABLE) &&
         (readonly == 1)) {
         PyErr_SetString(PyExc_BufferError,
diff --git a/Objects/bytearrayobject.c b/Objects/bytearrayobject.c
--- a/Objects/bytearrayobject.c
+++ b/Objects/bytearrayobject.c
@@ -60,18 +60,17 @@
 static int
 bytearray_getbuffer(PyByteArrayObject *obj, Py_buffer *view, int flags)
 {
-    int ret;
     void *ptr;
     if (view == NULL) {
-        obj->ob_exports++;
-        return 0;
+        PyErr_SetString(PyExc_BufferError,
+            "bytearray_getbuffer: view==NULL argument is obsolete");
+        return -1;
     }
     ptr = (void *) PyByteArray_AS_STRING(obj);
-    ret = PyBuffer_FillInfo(view, (PyObject*)obj, ptr, Py_SIZE(obj), 0, flags);
-    if (ret >= 0) {
-        obj->ob_exports++;
-    }
-    return ret;
+    /* cannot fail if view != NULL and readonly == 0 */
+    (void)PyBuffer_FillInfo(view, (PyObject*)obj, ptr, Py_SIZE(obj), 0, flags);
+    obj->ob_exports++;
+    return 0;
 }
 
 static void