diff --git a/Include/fileutils.h b/Include/fileutils.h
--- a/Include/fileutils.h
+++ b/Include/fileutils.h
@@ -6,6 +6,7 @@ extern "C" {
 #endif
 
 PyAPI_FUNC(PyObject *) _Py_device_encoding(int);
+PyAPI_FUNC(PyObject *) _Py_locale_encoding(void);
 
 PyAPI_FUNC(wchar_t *) _Py_char2wchar(
     const char *arg,
diff --git a/Python/fileutils.c b/Python/fileutils.c
--- a/Python/fileutils.c
+++ b/Python/fileutils.c
@@ -32,11 +32,56 @@ extern wchar_t* _Py_DecodeUTF8_surrogate
 int _Py_open_cloexec_works = -1;
 #endif
 
+static PyObject *
+get_codec_name(const char *encoding)
+{
+    /* Normalize codec name so that e.g. 'ANSI_X3.4-1968' becomes
+       'ascii'. */
+    PyObject *codec, *name;
+    _Py_IDENTIFIER(name);
+    codec = _PyCodec_Lookup(encoding);
+    if (!codec)
+        return NULL;
+    name = _PyObject_GetAttrId(codec, &PyId_name);
+    Py_DECREF(codec);
+    if (!name)
+        return NULL;
+    if (!PyUnicode_Check(name)) {
+        Py_DECREF(name);
+        PyErr_SetString(PyExc_TypeError,
+                        "'name' attribute should be a str object");
+        return NULL;
+    }
+    /* Issue #19846: 'ascii' gets turned into 'utf-8' */
+    if (PyUnicode_CompareWithASCIIString(name, "ascii"))
+        return name;
+    else {
+        Py_DECREF(name);
+        return PyUnicode_FromString("utf-8");
+    }
+}
+
+PyObject *
+_Py_locale_encoding()
+{
+#ifdef MS_WINDOWS
+    char codepage[100];
+    PyOS_snprintf(codepage, sizeof(codepage), "cp%d", GetACP());
+    return get_codec_name(codepage);
+#elif defined(HAVE_LANGINFO_H) && defined(CODESET)
+    char *codeset = nl_langinfo(CODESET);
+    if (codeset != NULL && codeset[0] != 0)
+        return get_codec_name(codeset);
+#endif
+    Py_RETURN_NONE;
+}
+
 PyObject *
 _Py_device_encoding(int fd)
 {
 #if defined(MS_WINDOWS)
     UINT cp;
+    char codepage[100];
 #endif
     if (!_PyVerify_fd(fd) || !isatty(fd)) {
         Py_RETURN_NONE;
@@ -50,16 +95,12 @@ PyObject *
         cp = 0;
     /* GetConsoleCP() and GetConsoleOutputCP() return 0 if the application
        has no console */
-    if (cp != 0)
-        return PyUnicode_FromFormat("cp%u", (unsigned int)cp);
-#elif defined(CODESET)
-    {
-        char *codeset = nl_langinfo(CODESET);
-        if (codeset != NULL && codeset[0] != 0)
-            return PyUnicode_FromString(codeset);
+    if (cp != 0) {
+        PyOS_snprintf(codepage, sizeof(codepage), "cp%d", cp);
+        return get_codec_name(codepage);
     }
 #endif
-    Py_RETURN_NONE;
+    return _Py_locale_encoding();
 }
 
 #if !defined(__APPLE__) && !defined(MS_WINDOWS)
diff --git a/Python/pythonrun.c b/Python/pythonrun.c
--- a/Python/pythonrun.c
+++ b/Python/pythonrun.c
@@ -216,55 +216,32 @@ add_flag(int flag, const char *envs)
 }
 
 static char*
-get_codec_name(const char *encoding)
+get_locale_encoding(void)
 {
-    char *name_utf8, *name_str;
-    PyObject *codec, *name = NULL;
-
-    codec = _PyCodec_Lookup(encoding);
-    if (!codec)
-        goto error;
-
-    name = _PyObject_GetAttrId(codec, &PyId_name);
-    Py_CLEAR(codec);
-    if (!name)
-        goto error;
-
-    name_utf8 = _PyUnicode_AsString(name);
-    if (name_utf8 == NULL)
-        goto error;
-    name_str = _PyMem_RawStrdup(name_utf8);
-    Py_DECREF(name);
-    if (name_str == NULL) {
-        PyErr_NoMemory();
+    PyObject *name = _Py_locale_encoding();
+    if (name == NULL)
+        return NULL;
+    else if (name == Py_None) {
+        Py_DECREF(name);
+        PyErr_SetString(PyExc_NotImplementedError,
+                        "could not determine locale encoding");
         return NULL;
     }
-    return name_str;
-
-error:
-    Py_XDECREF(codec);
-    Py_XDECREF(name);
-    return NULL;
-}
-
-static char*
-get_locale_encoding(void)
-{
-#ifdef MS_WINDOWS
-    char codepage[100];
-    PyOS_snprintf(codepage, sizeof(codepage), "cp%d", GetACP());
-    return get_codec_name(codepage);
-#elif defined(HAVE_LANGINFO_H) && defined(CODESET)
-    char* codeset = nl_langinfo(CODESET);
-    if (!codeset || codeset[0] == '\0') {
-        PyErr_SetString(PyExc_ValueError, "CODESET is not set or empty");
-        return NULL;
+    else {
+        char *name_utf8, *name_str;
+        name_utf8 = _PyUnicode_AsString(name);
+        if (name_utf8 == NULL) {
+            Py_DECREF(name);
+            return NULL;
+        }
+        name_str = _PyMem_RawStrdup(name_utf8);
+        Py_DECREF(name);
+        if (name_str == NULL) {
+            PyErr_NoMemory();
+            return NULL;
+        }
+        return name_str;
     }
-    return get_codec_name(codeset);
-#else
-    PyErr_SetNone(PyExc_NotImplementedError);
-    return NULL;
-#endif
 }
 
 static void