diff --git a/Modules/_io/fileio.c b/Modules/_io/fileio.c
index 7c8ba37..b9856b3 100644
--- a/Modules/_io/fileio.c
+++ b/Modules/_io/fileio.c
@@ -270,7 +270,14 @@
         if (!PyUnicode_FSDecoder(nameobj, &stringobj)) {
             return -1;
         }
+#if USE_UNICODE_WCHAR_CACHE
+_Py_COMP_DIAG_PUSH
+_Py_COMP_DIAG_IGNORE_DEPR_DECLS
         widename = PyUnicode_AsUnicode(stringobj);
+_Py_COMP_DIAG_POP
+#else /* USE_UNICODE_WCHAR_CACHE */
+        widename = PyUnicode_AsWideCharString(stringobj, NULL);
+#endif /* USE_UNICODE_WCHAR_CACHE */
         if (widename == NULL)
             return -1;
 #else
@@ -491,6 +498,11 @@
         internal_close(self);
 
  done:
+#ifdef MS_WINDOWS
+#if !USE_UNICODE_WCHAR_CACHE
+    PyMem_Free(widename);
+#endif /* USE_UNICODE_WCHAR_CACHE */
+#endif
     Py_CLEAR(stringobj);
     return ret;
 }
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index 1e4c31f..fca94a8 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -1668,6 +1668,7 @@
 
 static volatile int x;
 
+#if USE_UNICODE_WCHAR_CACHE
 /* Ignore use of deprecated APIs */
 _Py_COMP_DIAG_PUSH
 _Py_COMP_DIAG_IGNORE_DEPR_DECLS
@@ -1772,6 +1773,8 @@
     Py_DECREF(tuple);
     Py_RETURN_NONE;
 }
+_Py_COMP_DIAG_POP
+#endif /* USE_UNICODE_WCHAR_CACHE */
 
 static PyObject *
 test_widechar(PyObject *self, PyObject *Py_UNUSED(ignored))
@@ -1824,6 +1827,10 @@
         return raiseTestError("test_widechar",
                               "PyUnicode_FromWideChar(L\"\\U00110000\", 1) didn't fail");
 
+#if USE_UNICODE_WCHAR_CACHE
+/* Ignore use of deprecated APIs */
+_Py_COMP_DIAG_PUSH
+_Py_COMP_DIAG_IGNORE_DEPR_DECLS
     wide = PyUnicode_FromUnicode(invalid, 1);
     if (wide == NULL)
         PyErr_Clear();
@@ -1844,11 +1851,12 @@
         return raiseTestError("test_widechar",
                               "PyUnicode_Ready() didn't fail");
     }
+_Py_COMP_DIAG_POP
+#endif /* USE_UNICODE_WCHAR_CACHE */
 #endif
 
     Py_RETURN_NONE;
 }
-_Py_COMP_DIAG_POP
 
 static PyObject *
 unicode_aswidechar(PyObject *self, PyObject *args)
@@ -2024,6 +2032,7 @@
     return Py_BuildValue("(Nn)", to_copy, copied);
 }
 
+#if USE_UNICODE_WCHAR_CACHE
 /* Ignore use of deprecated APIs */
 _Py_COMP_DIAG_PUSH
 _Py_COMP_DIAG_IGNORE_DEPR_DECLS
@@ -2096,6 +2105,7 @@
     return u;
 }
 _Py_COMP_DIAG_POP
+#endif /* USE_UNICODE_WCHAR_CACHE */
 
 static PyObject *
 getargs_w_star(PyObject *self, PyObject *args)
@@ -5398,8 +5408,10 @@
     {"codec_incrementaldecoder",
      (PyCFunction)codec_incrementaldecoder,                      METH_VARARGS},
     {"test_s_code",             test_s_code,                     METH_NOARGS},
+#if USE_UNICODE_WCHAR_CACHE
     {"test_u_code",             test_u_code,                     METH_NOARGS},
     {"test_Z_code",             test_Z_code,                     METH_NOARGS},
+#endif /* USE_UNICODE_WCHAR_CACHE */
     {"test_widechar",           test_widechar,                   METH_NOARGS},
     {"unicode_aswidechar",      unicode_aswidechar,              METH_VARARGS},
     {"unicode_aswidecharstring",unicode_aswidecharstring,        METH_VARARGS},
@@ -5408,9 +5420,11 @@
     {"unicode_asutf8andsize",   unicode_asutf8andsize,           METH_VARARGS},
     {"unicode_findchar",        unicode_findchar,                METH_VARARGS},
     {"unicode_copycharacters",  unicode_copycharacters,          METH_VARARGS},
+#if USE_UNICODE_WCHAR_CACHE
     {"unicode_encodedecimal",   unicode_encodedecimal,           METH_VARARGS},
     {"unicode_transformdecimaltoascii", unicode_transformdecimaltoascii, METH_VARARGS},
     {"unicode_legacy_string",   unicode_legacy_string,           METH_VARARGS},
+#endif /* USE_UNICODE_WCHAR_CACHE */
     {"_test_thread_state",      test_thread_state,               METH_VARARGS},
     {"_pending_threadfunc",     pending_threadfunc,              METH_VARARGS},
 #ifdef HAVE_GETTIMEOFDAY
diff --git a/Modules/_winapi.c b/Modules/_winapi.c
index e1672c4..ddb11aa 100644
--- a/Modules/_winapi.c
+++ b/Modules/_winapi.c
@@ -164,10 +164,11 @@
 create_converter('BOOL', 'i') # F_BOOL used previously (always 'i')
 create_converter('DWORD', 'k') # F_DWORD is always "k" (which is much shorter)
 create_converter('LPCTSTR', 's')
-create_converter('LPCWSTR', 'u')
-create_converter('LPWSTR', 'u')
 create_converter('UINT', 'I') # F_UINT used previously (always 'I')
 
+class LPCWSTR_converter(Py_UNICODE_converter):
+    type = 'LPCWSTR'
+
 class HANDLE_return_converter(CReturnConverter):
     type = 'HANDLE'
 
@@ -197,7 +198,7 @@
         data.return_conversion.append(
             'return_value = HANDLE_TO_PYNUM(_return_value);\n')
 [python start generated code]*/
-/*[python end generated code: output=da39a3ee5e6b4b0d input=79464c61a31ae932]*/
+/*[python end generated code: output=da39a3ee5e6b4b0d input=011ee0c3a2244bfe]*/
 
 #include "clinic/_winapi.c.h"
 
@@ -520,15 +521,15 @@
 /*[clinic input]
 _winapi.CreateJunction
 
-    src_path: LPWSTR
-    dst_path: LPWSTR
+    src_path: LPCWSTR
+    dst_path: LPCWSTR
     /
 [clinic start generated code]*/
 
 static PyObject *
-_winapi_CreateJunction_impl(PyObject *module, LPWSTR src_path,
-                            LPWSTR dst_path)
-/*[clinic end generated code: output=66b7eb746e1dfa25 input=8cd1f9964b6e3d36]*/
+_winapi_CreateJunction_impl(PyObject *module, LPCWSTR src_path,
+                            LPCWSTR dst_path)
+/*[clinic end generated code: output=44b3f5e9bbcc4271 input=963d29b44b9384a7]*/
 {
     /* Privilege adjustment */
     HANDLE token = NULL;
diff --git a/Modules/clinic/_winapi.c.h b/Modules/clinic/_winapi.c.h
index 6022dfe..a9630d5 100644
--- a/Modules/clinic/_winapi.c.h
+++ b/Modules/clinic/_winapi.c.h
@@ -195,8 +195,8 @@
     LPCWSTR name;
     HANDLE _return_value;
 
-    if (!_PyArg_ParseStack(args, nargs, "" F_HANDLE "" F_POINTER "kkku:CreateFileMapping",
-        &file_handle, &security_attributes, &protect, &max_size_high, &max_size_low, &name)) {
+    if (!_PyArg_ParseStack(args, nargs, "" F_HANDLE "" F_POINTER "kkkO&:CreateFileMapping",
+        &file_handle, &security_attributes, &protect, &max_size_high, &max_size_low, _PyUnicode_WideCharString_Converter, &name)) {
         goto exit;
     }
     _return_value = _winapi_CreateFileMapping_impl(module, file_handle, security_attributes, protect, max_size_high, max_size_low, name);
@@ -209,6 +209,11 @@
     return_value = HANDLE_TO_PYNUM(_return_value);
 
 exit:
+    /* Cleanup for name */
+    #if !USE_UNICODE_WCHAR_CACHE
+    PyMem_Free((void *)name);
+    #endif /* USE_UNICODE_WCHAR_CACHE */
+
     return return_value;
 }
 
@@ -221,23 +226,55 @@
     {"CreateJunction", (PyCFunction)(void(*)(void))_winapi_CreateJunction, METH_FASTCALL, _winapi_CreateJunction__doc__},
 
 static PyObject *
-_winapi_CreateJunction_impl(PyObject *module, LPWSTR src_path,
-                            LPWSTR dst_path);
+_winapi_CreateJunction_impl(PyObject *module, LPCWSTR src_path,
+                            LPCWSTR dst_path);
 
 static PyObject *
 _winapi_CreateJunction(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
 {
     PyObject *return_value = NULL;
-    LPWSTR src_path;
-    LPWSTR dst_path;
+    LPCWSTR src_path;
+    LPCWSTR dst_path;
 
-    if (!_PyArg_ParseStack(args, nargs, "uu:CreateJunction",
-        &src_path, &dst_path)) {
+    if (!_PyArg_CheckPositional("CreateJunction", nargs, 2, 2)) {
+        goto exit;
+    }
+    if (!PyUnicode_Check(args[0])) {
+        _PyArg_BadArgument("CreateJunction", "argument 1", "str", args[0]);
+        goto exit;
+    }
+    #if USE_UNICODE_WCHAR_CACHE
+    src_path = _PyUnicode_AsUnicode(args[0]);
+    #else /* USE_UNICODE_WCHAR_CACHE */
+    src_path = PyUnicode_AsWideCharString(args[0], NULL);
+    #endif /* USE_UNICODE_WCHAR_CACHE */
+    if (src_path == NULL) {
+        goto exit;
+    }
+    if (!PyUnicode_Check(args[1])) {
+        _PyArg_BadArgument("CreateJunction", "argument 2", "str", args[1]);
+        goto exit;
+    }
+    #if USE_UNICODE_WCHAR_CACHE
+    dst_path = _PyUnicode_AsUnicode(args[1]);
+    #else /* USE_UNICODE_WCHAR_CACHE */
+    dst_path = PyUnicode_AsWideCharString(args[1], NULL);
+    #endif /* USE_UNICODE_WCHAR_CACHE */
+    if (dst_path == NULL) {
         goto exit;
     }
     return_value = _winapi_CreateJunction_impl(module, src_path, dst_path);
 
 exit:
+    /* Cleanup for src_path */
+    #if !USE_UNICODE_WCHAR_CACHE
+    PyMem_Free((void *)src_path);
+    #endif /* USE_UNICODE_WCHAR_CACHE */
+    /* Cleanup for dst_path */
+    #if !USE_UNICODE_WCHAR_CACHE
+    PyMem_Free((void *)dst_path);
+    #endif /* USE_UNICODE_WCHAR_CACHE */
+
     return return_value;
 }
 
@@ -715,8 +752,8 @@
     LPCWSTR name;
     HANDLE _return_value;
 
-    if (!_PyArg_ParseStack(args, nargs, "kiu:OpenFileMapping",
-        &desired_access, &inherit_handle, &name)) {
+    if (!_PyArg_ParseStack(args, nargs, "kiO&:OpenFileMapping",
+        &desired_access, &inherit_handle, _PyUnicode_WideCharString_Converter, &name)) {
         goto exit;
     }
     _return_value = _winapi_OpenFileMapping_impl(module, desired_access, inherit_handle, name);
@@ -729,6 +766,11 @@
     return_value = HANDLE_TO_PYNUM(_return_value);
 
 exit:
+    /* Cleanup for name */
+    #if !USE_UNICODE_WCHAR_CACHE
+    PyMem_Free((void *)name);
+    #endif /* USE_UNICODE_WCHAR_CACHE */
+
     return return_value;
 }
 
@@ -1106,4 +1148,4 @@
 exit:
     return return_value;
 }
-/*[clinic end generated code: output=db87076a32fa7abe input=a9049054013a1b77]*/
+/*[clinic end generated code: output=1f10e03f64ff9777 input=a9049054013a1b77]*/
diff --git a/Modules/overlapped.c b/Modules/overlapped.c
index 9c4e2da..4f0ba85 100644
--- a/Modules/overlapped.c
+++ b/Modules/overlapped.c
@@ -1291,6 +1291,7 @@
 static int
 parse_address(PyObject *obj, SOCKADDR *Address, int Length)
 {
+    PyObject *Host_obj;
     Py_UNICODE *Host;
     unsigned short Port;
     unsigned long FlowInfo;
@@ -1298,33 +1299,66 @@
 
     memset(Address, 0, Length);
 
-    if (PyArg_ParseTuple(obj, "uH", &Host, &Port))
-    {
+    switch (PyTuple_GET_SIZE(obj)) {
+    case 2: {
+        if (!PyArg_ParseTuple(obj, "UH", &Host_obj, &Port)) {
+            return -1;
+        }
+#if USE_UNICODE_WCHAR_CACHE
+        Host = (wchar_t *)_PyUnicode_AsUnicode(Host_obj);
+#else /* USE_UNICODE_WCHAR_CACHE */
+        Host = PyUnicode_AsWideCharString(Host_obj, NULL);
+#endif /* USE_UNICODE_WCHAR_CACHE */
+        if (Host == NULL) {
+            return -1;
+        }
         Address->sa_family = AF_INET;
         if (WSAStringToAddressW(Host, AF_INET, NULL, Address, &Length) < 0) {
             SetFromWindowsErr(WSAGetLastError());
-            return -1;
+            Length = -1;
         }
-        ((SOCKADDR_IN*)Address)->sin_port = htons(Port);
+        else {
+            ((SOCKADDR_IN*)Address)->sin_port = htons(Port);
+        }
+#if !USE_UNICODE_WCHAR_CACHE
+        PyMem_Free(Host);
+#endif /* USE_UNICODE_WCHAR_CACHE */
         return Length;
     }
-    else if (PyArg_ParseTuple(obj,
-                              "uHkk;ConnectEx(): illegal address_as_bytes "
-                              "argument", &Host, &Port, &FlowInfo, &ScopeId))
-    {
-        PyErr_Clear();
+    case 4: {
+        if (!PyArg_ParseTuple(obj,
+                "UHkk;ConnectEx(): illegal address_as_bytes argument",
+                &Host_obj, &Port, &FlowInfo, &ScopeId))
+        {
+            return -1;
+        }
+#if USE_UNICODE_WCHAR_CACHE
+        Host = (wchar_t *)_PyUnicode_AsUnicode(Host_obj);
+#else /* USE_UNICODE_WCHAR_CACHE */
+        Host = PyUnicode_AsWideCharString(Host_obj, NULL);
+#endif /* USE_UNICODE_WCHAR_CACHE */
+        if (Host == NULL) {
+            return -1;
+        }
         Address->sa_family = AF_INET6;
         if (WSAStringToAddressW(Host, AF_INET6, NULL, Address, &Length) < 0) {
             SetFromWindowsErr(WSAGetLastError());
-            return -1;
+            Length = -1;
         }
-        ((SOCKADDR_IN6*)Address)->sin6_port = htons(Port);
-        ((SOCKADDR_IN6*)Address)->sin6_flowinfo = FlowInfo;
-        ((SOCKADDR_IN6*)Address)->sin6_scope_id = ScopeId;
+        else {
+            ((SOCKADDR_IN6*)Address)->sin6_port = htons(Port);
+            ((SOCKADDR_IN6*)Address)->sin6_flowinfo = FlowInfo;
+            ((SOCKADDR_IN6*)Address)->sin6_scope_id = ScopeId;
+        }
+#if !USE_UNICODE_WCHAR_CACHE
+        PyMem_Free(Host);
+#endif /* USE_UNICODE_WCHAR_CACHE */
         return Length;
     }
-
-    return -1;
+    default:
+        PyErr_SetString(PyExc_ValueError, "illegal address_as_bytes argument");
+        return -1;
+    }
 }
 
 /*[clinic input]
diff --git a/Modules/posixmodule.c b/Modules/posixmodule.c
index a411f28..efd9954 100644
--- a/Modules/posixmodule.c
+++ b/Modules/posixmodule.c
@@ -988,6 +988,11 @@
 static void
 path_cleanup(path_t *path)
 {
+#if !USE_UNICODE_WCHAR_CACHE
+    wchar_t *wide = (wchar_t *)path->wide;
+    path->wide = NULL;
+    PyMem_Free(wide);
+#endif /* USE_UNICODE_WCHAR_CACHE */
     Py_CLEAR(path->object);
     Py_CLEAR(path->cleanup);
 }
@@ -1002,7 +1007,7 @@
     const char *narrow;
 #ifdef MS_WINDOWS
     PyObject *wo = NULL;
-    const wchar_t *wide;
+    wchar_t *wide = NULL;
 #endif
 
 #define FORMAT_EXCEPTION(exc, fmt) \
@@ -1075,7 +1080,14 @@
 
     if (is_unicode) {
 #ifdef MS_WINDOWS
+#if USE_UNICODE_WCHAR_CACHE
+_Py_COMP_DIAG_PUSH
+_Py_COMP_DIAG_IGNORE_DEPR_DECLS
         wide = PyUnicode_AsUnicodeAndSize(o, &length);
+_Py_COMP_DIAG_POP
+#else /* USE_UNICODE_WCHAR_CACHE */
+        wide = PyUnicode_AsWideCharString(o, &length);
+#endif /* USE_UNICODE_WCHAR_CACHE */
         if (!wide) {
             goto error_exit;
         }
@@ -1091,6 +1103,9 @@
         path->wide = wide;
         path->narrow = FALSE;
         path->fd = -1;
+#if !USE_UNICODE_WCHAR_CACHE
+        wide = NULL;
+#endif /* USE_UNICODE_WCHAR_CACHE */
         goto success_exit;
 #else
         if (!PyUnicode_FSConverter(o, &bytes)) {
@@ -1166,7 +1181,15 @@
         goto error_exit;
     }
 
+#if USE_UNICODE_WCHAR_CACHE
+_Py_COMP_DIAG_PUSH
+_Py_COMP_DIAG_IGNORE_DEPR_DECLS
     wide = PyUnicode_AsUnicodeAndSize(wo, &length);
+_Py_COMP_DIAG_POP
+#else /* USE_UNICODE_WCHAR_CACHE */
+    wide = PyUnicode_AsWideCharString(wo, &length);
+    Py_DECREF(wo);
+#endif /* USE_UNICODE_WCHAR_CACHE */
     if (!wide) {
         goto error_exit;
     }
@@ -1180,8 +1203,12 @@
     }
     path->wide = wide;
     path->narrow = TRUE;
-    path->cleanup = wo;
     Py_DECREF(bytes);
+#if USE_UNICODE_WCHAR_CACHE
+    path->cleanup = wo;
+#else /* USE_UNICODE_WCHAR_CACHE */
+    wide = NULL;
+#endif /* USE_UNICODE_WCHAR_CACHE */
 #else
     path->wide = NULL;
     path->narrow = narrow;
@@ -1205,7 +1232,11 @@
     Py_XDECREF(o);
     Py_XDECREF(bytes);
 #ifdef MS_WINDOWS
+#if USE_UNICODE_WCHAR_CACHE
     Py_XDECREF(wo);
+#else /* USE_UNICODE_WCHAR_CACHE */
+    PyMem_Free(wide);
+#endif /* USE_UNICODE_WCHAR_CACHE */
 #endif
     return 0;
 }
@@ -12824,7 +12855,15 @@
 #ifdef MS_WINDOWS
     if (!PyUnicode_FSDecoder(self->path, &ub))
         return NULL;
+#if USE_UNICODE_WCHAR_CACHE
+_Py_COMP_DIAG_PUSH
+_Py_COMP_DIAG_IGNORE_DEPR_DECLS
     const wchar_t *path = PyUnicode_AsUnicode(ub);
+_Py_COMP_DIAG_POP
+#else /* USE_UNICODE_WCHAR_CACHE */
+    wchar_t *path = PyUnicode_AsWideCharString(ub, NULL);
+    Py_DECREF(ub);
+#endif /* USE_UNICODE_WCHAR_CACHE */
 #else /* POSIX */
     if (!PyUnicode_FSConverter(self->path, &ub))
         return NULL;
@@ -12834,6 +12873,7 @@
         result = fstatat(self->dir_fd, path, &st,
                          follow_symlinks ? 0 : AT_SYMLINK_NOFOLLOW);
 #else
+        Py_DECREF(ub);
         PyErr_SetString(PyExc_NotImplementedError, "can't fetch stat");
         return NULL;
 #endif /* HAVE_FSTATAT */
@@ -12846,7 +12886,11 @@
         else
             result = LSTAT(path, &st);
     }
+#if defined(MS_WINDOWS) && !USE_UNICODE_WCHAR_CACHE
+    PyMem_Free(path);
+#else /* USE_UNICODE_WCHAR_CACHE */
     Py_DECREF(ub);
+#endif /* USE_UNICODE_WCHAR_CACHE */
 
     if (result != 0)
         return path_object_error(self->path);
@@ -13035,15 +13079,24 @@
 #ifdef MS_WINDOWS
     if (!self->got_file_index) {
         PyObject *unicode;
-        const wchar_t *path;
         STRUCT_STAT stat;
         int result;
 
         if (!PyUnicode_FSDecoder(self->path, &unicode))
             return NULL;
-        path = PyUnicode_AsUnicode(unicode);
+#if USE_UNICODE_WCHAR_CACHE
+_Py_COMP_DIAG_PUSH
+_Py_COMP_DIAG_IGNORE_DEPR_DECLS
+        const wchar_t *path = PyUnicode_AsUnicode(unicode);
         result = LSTAT(path, &stat);
         Py_DECREF(unicode);
+_Py_COMP_DIAG_POP
+#else /* USE_UNICODE_WCHAR_CACHE */
+        wchar_t *path = PyUnicode_AsWideCharString(unicode, NULL);
+        Py_DECREF(unicode);
+        result = LSTAT(path, &stat);
+        PyMem_Free(path);
+#endif /* USE_UNICODE_WCHAR_CACHE */
 
         if (result != 0)
             return path_object_error(self->path);
@@ -13597,10 +13650,9 @@
     iterator->dirp = NULL;
 #endif
 
-    memcpy(&iterator->path, path, sizeof(path_t));
     /* Move the ownership to iterator->path */
-    path->object = NULL;
-    path->cleanup = NULL;
+    memcpy(&iterator->path, path, sizeof(path_t));
+    memset(path, 0, sizeof(path_t));
 
 #ifdef MS_WINDOWS
     iterator->first_time = 1;
@@ -13622,9 +13674,9 @@
 #else /* POSIX */
     errno = 0;
 #ifdef HAVE_FDOPENDIR
-    if (path->fd != -1) {
+    if (iterator->path.fd != -1) {
         /* closedir() closes the FD, so we duplicate it */
-        fd = _Py_dup(path->fd);
+        fd = _Py_dup(iterator->path.fd);
         if (fd == -1)
             goto error;