diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 3238d1e..a03ca9a 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -206,22 +206,6 @@ extern "C" {
 #  define OVERALLOCATE_FACTOR 4
 #endif
 
-/* bpo-40521: Interned strings are shared by all interpreters. */
-#ifndef EXPERIMENTAL_ISOLATED_SUBINTERPRETERS
-#  define INTERNED_STRINGS
-#endif
-
-/* This dictionary holds all interned unicode strings.  Note that references
-   to strings in this dictionary are *not* counted in the string's ob_refcnt.
-   When the interned string reaches a refcnt of 0 the string deallocation
-   function will delete the reference from this dictionary.
-
-   Another way to look at this is that to say that the actual reference
-   count of a string is:  s->ob_refcnt + (s->state ? 2 : 0)
-*/
-#ifdef INTERNED_STRINGS
-static PyObject *interned = NULL;
-#endif
 
 static struct _Py_unicode_state*
 get_unicode_state(void)
@@ -1946,7 +1930,8 @@ unicode_dealloc(PyObject *unicode)
         break;
 
     case SSTATE_INTERNED_MORTAL:
-#ifdef INTERNED_STRINGS
+    {
+        struct _Py_unicode_state *state = get_unicode_state();
         /* Revive the dead object temporarily. PyDict_DelItem() removes two
            references (key and value) which were ignored by
            PyUnicode_InternInPlace(). Use refcnt=3 rather than refcnt=2
@@ -1954,14 +1939,14 @@ unicode_dealloc(PyObject *unicode)
            PyDict_DelItem(). */
         assert(Py_REFCNT(unicode) == 0);
         Py_SET_REFCNT(unicode, 3);
-        if (PyDict_DelItem(interned, unicode) != 0) {
+        if (PyDict_DelItem(state->interned, unicode) != 0) {
             _PyErr_WriteUnraisableMsg("deletion of interned string failed",
                                       NULL);
         }
         assert(Py_REFCNT(unicode) == 1);
         Py_SET_REFCNT(unicode, 0);
-#endif
         break;
+    }
 
     case SSTATE_INTERNED_IMMORTAL:
         _PyObject_ASSERT_FAILED_MSG(unicode, "Immortal interned string died");
@@ -11536,12 +11521,11 @@ _PyUnicode_EqualToASCIIId(PyObject *left, _Py_Identifier *right)
     if (PyUnicode_CHECK_INTERNED(left))
         return 0;
 
-#ifdef INTERNED_STRINGS
     assert(_PyUnicode_HASH(right_uni) != -1);
     Py_hash_t hash = _PyUnicode_HASH(left);
-    if (hash != -1 && hash != _PyUnicode_HASH(right_uni))
+    if (hash != -1 && hash != _PyUnicode_HASH(right_uni)) {
         return 0;
-#endif
+    }
 
     return unicode_compare_eq(left, right_uni);
 }
@@ -15765,23 +15749,21 @@ PyUnicode_InternInPlace(PyObject **p)
         return;
     }
 
-#ifdef INTERNED_STRINGS
     if (PyUnicode_READY(s) == -1) {
         PyErr_Clear();
         return;
     }
 
-    if (interned == NULL) {
-        interned = PyDict_New();
-        if (interned == NULL) {
+    struct _Py_unicode_state *state = get_unicode_state();
+    if (state->interned == NULL) {
+        state->interned = PyDict_New();
+        if (state->interned == NULL) {
             PyErr_Clear(); /* Don't leave an exception */
             return;
         }
     }
 
-    PyObject *t;
-    t = PyDict_SetDefault(interned, s, s);
-
+    PyObject *t = PyDict_SetDefault(state->interned, s, s);
     if (t == NULL) {
         PyErr_Clear();
         return;
@@ -15798,13 +15780,9 @@ PyUnicode_InternInPlace(PyObject **p)
        this. */
     Py_SET_REFCNT(s, Py_REFCNT(s) - 2);
     _PyUnicode_STATE(s).interned = SSTATE_INTERNED_MORTAL;
-#else
-    // PyDict expects that interned strings have their hash
-    // (PyASCIIObject.hash) already computed.
-    (void)unicode_hash(s);
-#endif
 }
 
+
 void
 PyUnicode_InternImmortal(PyObject **p)
 {
@@ -15838,35 +15816,25 @@ PyUnicode_InternFromString(const char *cp)
 void
 _PyUnicode_ClearInterned(PyThreadState *tstate)
 {
-    if (!_Py_IsMainInterpreter(tstate)) {
-        // interned dict is shared by all interpreters
+    struct _Py_unicode_state *state = &tstate->interp->unicode;
+    if (state->interned == NULL) {
         return;
     }
-
-    if (interned == NULL) {
-        return;
-    }
-    assert(PyDict_CheckExact(interned));
-
-    PyObject *keys = PyDict_Keys(interned);
-    if (keys == NULL) {
-        PyErr_Clear();
-        return;
-    }
-    assert(PyList_CheckExact(keys));
+    assert(PyDict_CheckExact(state->interned));
 
     /* Interned unicode strings are not forcibly deallocated; rather, we give
        them their stolen references back, and then clear and DECREF the
        interned dict. */
 
-    Py_ssize_t n = PyList_GET_SIZE(keys);
 #ifdef INTERNED_STATS
-    fprintf(stderr, "releasing %zd interned strings\n", n);
+    fprintf(stderr, "releasing %zd interned strings\n",
+            PyDict_GET_SIZE(state->interned));
 
     Py_ssize_t immortal_size = 0, mortal_size = 0;
 #endif
-    for (Py_ssize_t i = 0; i < n; i++) {
-        PyObject *s = PyList_GET_ITEM(keys, i);
+    Py_ssize_t pos = 0;
+    PyObject *s, *ignored_value;
+    while (PyDict_Next(state->interned, &pos, &s, &ignored_value)) {
         assert(PyUnicode_IS_READY(s));
 
         switch (PyUnicode_CHECK_INTERNED(s)) {
@@ -15896,10 +15864,9 @@ _PyUnicode_ClearInterned(PyThreadState *tstate)
             "total size of all interned strings: %zd/%zd mortal/immortal\n",
             mortal_size, immortal_size);
 #endif
-    Py_DECREF(keys);
 
-    PyDict_Clear(interned);
-    Py_CLEAR(interned);
+    PyDict_Clear(state->interned);
+    Py_CLEAR(state->interned);
 }
 
 
@@ -16269,19 +16236,19 @@ _PyUnicode_EnableLegacyWindowsFSEncoding(void)
 void
 _PyUnicode_Fini(PyThreadState *tstate)
 {
-    // _PyUnicode_ClearInterned() must be called before
-
     struct _Py_unicode_state *state = &tstate->interp->unicode;
 
-    Py_CLEAR(state->empty_string);
+    // _PyUnicode_ClearInterned() must be called before
+    assert(state->interned == NULL);
+
+    _PyUnicode_FiniEncodings(&state->fs_codec);
+
+    unicode_clear_identifiers(tstate);
 
     for (Py_ssize_t i = 0; i < 256; i++) {
         Py_CLEAR(state->latin1[i]);
     }
-
-    unicode_clear_identifiers(tstate);
-
-    _PyUnicode_FiniEncodings(&tstate->interp->unicode.fs_codec);
+    Py_CLEAR(state->empty_string);
 }