diff --git a/Doc/library/codecs.rst b/Doc/library/codecs.rst
index 7218d3a..b8a8ccc 100644
--- a/Doc/library/codecs.rst
+++ b/Doc/library/codecs.rst
@@ -74,7 +74,7 @@
    continue without further notice), ``'xmlcharrefreplace'`` (replace with the
    appropriate XML character reference (for encoding only)),
    ``'backslashreplace'`` (replace with backslashed escape sequences (for
-   encoding only)), ``'surrogateescape'`` (replae with surrogate U+DCxx, see
+   encoding only)), ``'surrogateescape'`` (replace with surrogate U+DCxx, see
    :pep:`383`) as well as any other error handling name defined via
    :func:`register_error`.
 
diff --git a/Lib/test/test_memoryio.py b/Lib/test/test_memoryio.py
index 0d044e9..187adad 100644
--- a/Lib/test/test_memoryio.py
+++ b/Lib/test/test_memoryio.py
@@ -416,6 +416,10 @@
         self.assertEqual(memio.write(a), 10)
         self.assertEqual(memio.getvalue(), buf)
 
+    def test_issue5449(self):
+        buf = self.buftype("1234567890")
+        self.ioclass(initial_bytes=buf)
+        self.assertRaises(TypeError, self.ioclass, buf, foo=None)
 
 class PyStringIOTest(MemoryTestMixin, MemorySeekTestMixin, unittest.TestCase):
     buftype = str
diff --git a/Modules/_io/bytesio.c b/Modules/_io/bytesio.c
index 7675846..cafe4a2 100644
--- a/Modules/_io/bytesio.c
+++ b/Modules/_io/bytesio.c
@@ -642,9 +642,11 @@
 static int
 bytesio_init(bytesio *self, PyObject *args, PyObject *kwds)
 {
+    char *kwlist[] = {"initial_bytes", NULL};
     PyObject *initvalue = NULL;
 
-    if (!PyArg_ParseTuple(args, "|O:BytesIO", &initvalue))
+    if (!PyArg_ParseTupleAndKeywords(args, kwds, "|O:BytesIO", kwlist,
+                                     &initvalue))
         return -1;
 
     /* In case, __init__ is called multiple times. */