diff --git a/Doc/whatsnew/3.13.rst b/Doc/whatsnew/3.13.rst
index 24a53b7700b573..54f007f7d12551 100644
--- a/Doc/whatsnew/3.13.rst
+++ b/Doc/whatsnew/3.13.rst
@@ -933,8 +933,8 @@ Build Changes
   library, GCC built-in atomic functions, or MSVC interlocked intrinsics.
 
 * The ``errno``, ``md5``, ``resource``, ``winsound``, ``_ctypes_test``,
-  ``_stat`` and ``_testimportmultiple`` C extensions are now built with the
-  :ref:`limited C API <limited-c-api>`.
+  ``_scproxy``, ``_stat`` and ``_testimportmultiple`` C extensions are now
+  built with the :ref:`limited C API <limited-c-api>`.
   (Contributed by Victor Stinner in :gh:`85283`.)
 
 
diff --git a/Misc/NEWS.d/next/Build/2023-10-17-01-56-11.gh-issue-85283.V156T2.rst b/Misc/NEWS.d/next/Build/2023-10-17-01-56-11.gh-issue-85283.V156T2.rst
index 3e85d85d37a2e6..cd26f7be288399 100644
--- a/Misc/NEWS.d/next/Build/2023-10-17-01-56-11.gh-issue-85283.V156T2.rst
+++ b/Misc/NEWS.d/next/Build/2023-10-17-01-56-11.gh-issue-85283.V156T2.rst
@@ -1,4 +1,4 @@
-The ``errno``, ``md5``, ``resource``, ``winsound``, ``_ctypes_test``, ``_stat``
-and ``_testimportmultiple`` C extensions are now built with the :ref:`limited C
-API <limited-c-api>`.
+The ``errno``, ``md5``, ``resource``, ``winsound``, ``_ctypes_test``,
+``_scproxy``, ``_stat`` and ``_testimportmultiple`` C extensions are now built
+with the :ref:`limited C API <limited-c-api>`.
 Patch by Victor Stinner.
diff --git a/Modules/_scproxy.c b/Modules/_scproxy.c
index 6cc09088bdc869..2f1b8618eb9fcc 100644
--- a/Modules/_scproxy.c
+++ b/Modules/_scproxy.c
@@ -2,6 +2,10 @@
  * Helper method for urllib to fetch the proxy configuration settings
  * using the SystemConfiguration framework.
  */
+
+// Need limited C API version 3.13 for Py_MOD_PER_INTERPRETER_GIL_SUPPORTED
+#define Py_LIMITED_API 0x030d0000
+
 #include <Python.h>
 #include <SystemConfiguration/SystemConfiguration.h>
 
@@ -21,8 +25,7 @@ cfstring_to_pystring(CFStringRef ref)
 
     s = CFStringGetCStringPtr(ref, kCFStringEncodingUTF8);
     if (s) {
-        return PyUnicode_DecodeUTF8(
-                        s, strlen(s), NULL);
+        return PyUnicode_DecodeUTF8(s, strlen(s), NULL);
 
     } else {
         CFIndex len = CFStringGetLength(ref);
@@ -43,8 +46,7 @@ cfstring_to_pystring(CFStringRef ref)
             PyMem_Free(buf);
             return NULL;
         } else {
-            result = PyUnicode_DecodeUTF8(
-                            buf, strlen(buf), NULL);
+            result = PyUnicode_DecodeUTF8(buf, strlen(buf), NULL);
             PyMem_Free(buf);
         }
         return result;
@@ -84,7 +86,7 @@ get_proxy_settings(PyObject* Py_UNUSED(mod), PyObject *Py_UNUSED(ignored))
     if (v == NULL) goto error;
 
     r = PyDict_SetItemString(result, "exclude_simple", v);
-    Py_SETREF(v, NULL);
+    Py_CLEAR(v);
     if (r == -1) goto error;
 
     anArray = CFDictionaryGetValue(proxyDict,
@@ -104,13 +106,11 @@ get_proxy_settings(PyObject* Py_UNUSED(mod), PyObject *Py_UNUSED(ignored))
 
             aString = CFArrayGetValueAtIndex(anArray, i);
             if (aString == NULL) {
-                PyTuple_SetItem(v, i, Py_None);
-                Py_INCREF(Py_None);
+                PyTuple_SetItem(v, i, Py_NewRef(Py_None));
             } else {
                 PyObject* t = cfstring_to_pystring(aString);
                 if (!t) {
-                    PyTuple_SetItem(v, i, Py_None);
-                    Py_INCREF(Py_None);
+                    PyTuple_SetItem(v, i, Py_NewRef(Py_None));
                 } else {
                     PyTuple_SetItem(v, i, t);
                 }
@@ -148,15 +148,13 @@ set_proxy(PyObject* proxies, const char* proto, CFDictionaryRef proxyDict,
             if (h) {
                 if (aNum) {
                     int32_t port = cfnum_to_int32(aNum);
-                    v = PyUnicode_FromFormat("http://%U:%ld",
-                        h, (long)port);
+                    v = PyUnicode_FromFormat("http://%U:%ld", h, (long)port);
                 } else {
                     v = PyUnicode_FromFormat("http://%U", h);
                 }
                 Py_DECREF(h);
                 if (!v) return -1;
-                r = PyDict_SetItemString(proxies, proto,
-                    v);
+                r = PyDict_SetItemString(proxies, proto, v);
                 Py_DECREF(v);
                 return r;
             }