diff --git a/Objects/abstract.c b/Objects/abstract.c
index c0298a8..dd05fe1 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -2600,6 +2600,11 @@
 	static PyObject *name = NULL;
 	PyObject *t, *v, *tb;
 	PyObject *checker;
+
+	/* Quick test for an exact match */
+	if (Py_TYPE(inst) == (PyTypeObject *)cls)
+		return 1;
+
 	PyErr_Fetch(&t, &v, &tb);
 
 	if (name == NULL) {