diff --git a/Lib/test/test_capi.py b/Lib/test/test_capi.py
index 5b8b9f6..73e167a 100644
--- a/Lib/test/test_capi.py
+++ b/Lib/test/test_capi.py
@@ -477,6 +477,11 @@
         self.assertEqual(ref(), inst)
         self.assertEqual(inst.weakreflist, ref)
 
+    def test_heaptype_with_buffer(self):
+        inst = _testcapi.HeapCTypeWithBuffer()
+        b = bytes(inst)
+        self.assertEqual(b, b"1234")
+
     def test_c_subclass_of_heap_ctype_with_tpdealloc_decrefs_once(self):
         subclass_instance = _testcapi.HeapCTypeSubclass()
         type_refcnt = sys.getrefcount(_testcapi.HeapCTypeSubclass)