diff --git a/Misc/NEWS.d/next/Core and Builtins/2022-11-09-16-02-27.gh-issue-99293.oPstNV.rst b/Misc/NEWS.d/next/Core and Builtins/2022-11-09-16-02-27.gh-issue-99293.oPstNV.rst
new file mode 100644
index 00000000000000..730e1a79c407ac
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2022-11-09-16-02-27.gh-issue-99293.oPstNV.rst	
@@ -0,0 +1 @@
+Fix an issue where extension modules could inadvertently trigger an assertion error in typeobject.c by clearing the Py_TPFLAGS_VALID_VERSION_TAG tp_flag without clearing the tp_version_tag field. (Extension modules should use PyType_Modified() instead, however.)
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index e2e40b5c15297d..d0f241d5b7c40b 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -4176,12 +4176,17 @@ _PyType_Lookup(PyTypeObject *type, PyObject *name)
     unsigned int h = MCACHE_HASH_METHOD(type, name);
     struct type_cache *cache = get_type_cache();
     struct type_cache_entry *entry = &cache->hashtable[h];
+    /* Some extension modules (e.g. those generated by SWIG) don't always
+     * change/clear tp_version_tag when they clear the
+     * Py_TPFLAGS_VALID_VERSION_TAG tp_flag, so check both tp_version_tag
+     * and the tp_flag. (Invalidated cache entries are replaced below.)
+     */
     if (entry->version == type->tp_version_tag &&
-        entry->name == name) {
+        entry->name == name &&
+        _PyType_HasFeature(type, Py_TPFLAGS_VALID_VERSION_TAG)) {
 #if MCACHE_STATS
         cache->hits++;
 #endif
-        assert(_PyType_HasFeature(type, Py_TPFLAGS_VALID_VERSION_TAG));
         return entry->value;
     }