diff --git a/PC/winreg.c b/PC/winreg.c
index efdf8addc06186..b4842a70c4980b 100644
--- a/PC/winreg.c
+++ b/PC/winreg.c
@@ -428,7 +428,9 @@ PyHKEY_Close(winreg_state *st, PyObject *ob_handle)
     if (PyHKEY_Check(st, ob_handle)) {
         ((PyHKEYObject*)ob_handle)->hkey = 0;
     }
+    Py_BEGIN_ALLOW_THREADS
     rc = key ? RegCloseKey(key) : ERROR_SUCCESS;
+    Py_END_ALLOW_THREADS
     if (rc != ERROR_SUCCESS)
         PyErr_SetFromWindowsErrWithFunction(rc, "RegCloseKey");
     return rc == ERROR_SUCCESS;
@@ -501,14 +503,21 @@ PyWinObject_CloseHKEY(winreg_state *st, PyObject *obHandle)
     }
 #if SIZEOF_LONG >= SIZEOF_HKEY
     else if (PyLong_Check(obHandle)) {
-        long rc = RegCloseKey((HKEY)PyLong_AsLong(obHandle));
+        long rc;
+        Py_BEGIN_ALLOW_THREADS
+        rc = RegCloseKey((HKEY)PyLong_AsLong(obHandle));
+        Py_END_ALLOW_THREADS
         ok = (rc == ERROR_SUCCESS);
         if (!ok)
             PyErr_SetFromWindowsErrWithFunction(rc, "RegCloseKey");
     }
 #else
     else if (PyLong_Check(obHandle)) {
-        long rc = RegCloseKey((HKEY)PyLong_AsVoidPtr(obHandle));
+        long rc;
+        HKEY hkey = (HKEY)PyLong_AsVoidPtr(obHandle);
+        Py_BEGIN_ALLOW_THREADS
+        rc = RegCloseKey(hkey);
+        Py_END_ALLOW_THREADS
         ok = (rc == ERROR_SUCCESS);
         if (!ok)
             PyErr_SetFromWindowsErrWithFunction(rc, "RegCloseKey");
@@ -926,7 +935,9 @@ winreg_CreateKey_impl(PyObject *module, HKEY key, const wchar_t *sub_key)
                     (Py_ssize_t)KEY_WRITE) < 0) {
         return NULL;
     }
+    Py_BEGIN_ALLOW_THREADS
     rc = RegCreateKeyW(key, sub_key, &retKey);
+    Py_END_ALLOW_THREADS
     if (rc != ERROR_SUCCESS) {
         PyErr_SetFromWindowsErrWithFunction(rc, "CreateKey");
         return NULL;
@@ -975,8 +986,10 @@ winreg_CreateKeyEx_impl(PyObject *module, HKEY key, const wchar_t *sub_key,
                     (Py_ssize_t)access) < 0) {
         return NULL;
     }
+    Py_BEGIN_ALLOW_THREADS
     rc = RegCreateKeyExW(key, sub_key, reserved, NULL, 0,
                          access, NULL, &retKey, NULL);
+    Py_END_ALLOW_THREADS
     if (rc != ERROR_SUCCESS) {
         PyErr_SetFromWindowsErrWithFunction(rc, "CreateKeyEx");
         return NULL;
@@ -1189,10 +1202,12 @@ winreg_EnumValue_impl(PyObject *module, HKEY key, int index)
                     (Py_ssize_t)key, index) < 0) {
         return NULL;
     }
-    if ((rc = RegQueryInfoKeyW(key, NULL, NULL, NULL, NULL, NULL, NULL,
-                              NULL,
-                              &retValueSize, &retDataSize, NULL, NULL))
-        != ERROR_SUCCESS)
+
+    Py_BEGIN_ALLOW_THREADS
+    rc = RegQueryInfoKeyW(key, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
+                          &retValueSize, &retDataSize, NULL, NULL);
+    Py_END_ALLOW_THREADS
+    if (rc != ERROR_SUCCESS)
         return PyErr_SetFromWindowsErrWithFunction(rc,
                                                    "RegQueryInfoKey");
     ++retValueSize;    /* include null terminators */
@@ -1479,9 +1494,11 @@ winreg_QueryInfoKey_impl(PyObject *module, HKEY key)
     if (PySys_Audit("winreg.QueryInfoKey", "n", (Py_ssize_t)key) < 0) {
         return NULL;
     }
-    if ((rc = RegQueryInfoKeyW(key, NULL, NULL, 0, &nSubKeys, NULL, NULL,
-                               &nValues,  NULL,  NULL, NULL, &ft))
-                               != ERROR_SUCCESS) {
+    Py_BEGIN_ALLOW_THREADS
+    rc = RegQueryInfoKeyW(key, NULL, NULL, 0, &nSubKeys, NULL, NULL,
+                          &nValues,  NULL,  NULL, NULL, &ft);
+    Py_END_ALLOW_THREADS
+    if (rc != ERROR_SUCCESS) {
         return PyErr_SetFromWindowsErrWithFunction(rc, "RegQueryInfoKey");
     }
     li.LowPart = ft.dwLowDateTime;
@@ -1589,7 +1606,9 @@ winreg_QueryValue_impl(PyObject *module, HKEY key, const wchar_t *sub_key)
         PyMem_Free(pbuf);
     }
     if (childKey != key) {
+        Py_BEGIN_ALLOW_THREADS
         RegCloseKey(childKey);
+        Py_END_ALLOW_THREADS
     }
     return result;
 }
@@ -1627,7 +1646,9 @@ winreg_QueryValueEx_impl(PyObject *module, HKEY key, const wchar_t *name)
                     (Py_ssize_t)key, NULL, name) < 0) {
         return NULL;
     }
+    Py_BEGIN_ALLOW_THREADS
     rc = RegQueryValueExW(key, name, NULL, NULL, NULL, &bufSize);
+    Py_END_ALLOW_THREADS
     if (rc == ERROR_MORE_DATA)
         bufSize = 256;
     else if (rc != ERROR_SUCCESS)
@@ -1639,8 +1660,10 @@ winreg_QueryValueEx_impl(PyObject *module, HKEY key, const wchar_t *name)
 
     while (1) {
         retSize = bufSize;
+        Py_BEGIN_ALLOW_THREADS
         rc = RegQueryValueExW(key, name, NULL, &typ,
                              (BYTE *)retBuf, &retSize);
+        Py_END_ALLOW_THREADS
         if (rc != ERROR_MORE_DATA)
             break;