diff --git a/Python/errors.c b/Python/errors.c
index 1463cdc..01304d2 100644
--- a/Python/errors.c
+++ b/Python/errors.c
@@ -582,9 +582,7 @@
 PyObject *
 PyErr_SetFromErrnoWithUnicodeFilename(PyObject *exc, const Py_UNICODE *filename)
 {
-    PyObject *name = filename ?
-                     PyUnicode_FromUnicode(filename, wcslen(filename)) :
-             NULL;
+    PyObject *name = filename ? PyUnicode_FromWideChar(filename, -1) : NULL;
     PyObject *result = PyErr_SetFromErrnoWithFilenameObjects(exc, name, NULL);
     Py_XDECREF(name);
     return result;
@@ -691,9 +689,7 @@
     int ierr,
     const Py_UNICODE *filename)
 {
-    PyObject *name = filename ?
-                     PyUnicode_FromUnicode(filename, wcslen(filename)) :
-             NULL;
+    PyObject *name = filename ? PyUnicode_FromWideChar(filename, -1) : NULL;
     PyObject *ret = PyErr_SetExcFromWindowsErrWithFilenameObjects(exc,
                                                                  ierr,
                                                                  name,
@@ -729,9 +725,7 @@
     int ierr,
     const Py_UNICODE *filename)
 {
-    PyObject *name = filename ?
-                     PyUnicode_FromUnicode(filename, wcslen(filename)) :
-             NULL;
+    PyObject *name = filename ? PyUnicode_FromWideChar(filename, -1) : NULL;
     PyObject *result = PyErr_SetExcFromWindowsErrWithFilenameObjects(
                                                   PyExc_OSError,
                                                   ierr, name, NULL);
diff --git a/Python/getargs.c b/Python/getargs.c
index a6636f4..c552d0f 100644
--- a/Python/getargs.c
+++ b/Python/getargs.c
@@ -1027,7 +1027,7 @@
                 *p = PyUnicode_AsUnicodeAndSize(arg, &len);
                 if (*p == NULL)
                     RETURN_ERR_OCCURRED;
-                if (Py_UNICODE_strlen(*p) != (size_t)len) {
+                if (wcslen(*p) != (size_t)len) {
                     PyErr_SetString(PyExc_ValueError, "embedded null character");
                     RETURN_ERR_OCCURRED;
                 }
@@ -1074,9 +1074,14 @@
             (PyBytes_Check(arg) || PyByteArray_Check(arg))) {
             s = arg;
             Py_INCREF(s);
-            if (PyObject_AsCharBuffer(s, &ptr, &size) < 0)
-                return converterr("(AsCharBuffer failed)",
-                                  arg, msgbuf, bufsize);
+            if (PyBytes_Check(arg)) {
+                size = PyBytes_GET_SIZE(s);
+                ptr = PyBytes_AS_STRING(s);
+            }
+            else {
+                size = PyByteArray_GET_SIZE(s);
+                ptr = PyByteArray_AS_STRING(s);
+            }
         }
         else if (PyUnicode_Check(arg)) {
             /* Encode object; use default error handling */
diff --git a/Python/modsupport.c b/Python/modsupport.c
index aabee8f..35b529b 100644
--- a/Python/modsupport.c
+++ b/Python/modsupport.c
@@ -286,8 +286,8 @@
             }
             else {
                 if (n < 0)
-                    n = Py_UNICODE_strlen(u);
-                v = PyUnicode_FromUnicode(u, n);
+                    n = wcslen(u);
+                v = PyUnicode_FromWideChar(u, n);
             }
             return v;
         }