diff --git a/Python/Python-ast.c b/Python/Python-ast.c
index 1178d74..d9e13e2 100644
--- a/Python/Python-ast.c
+++ b/Python/Python-ast.c
@@ -460,6 +460,12 @@
     PyObject *dict;
 } AST_object;
 
+static void
+ast_dealloc(AST_object *self)
+{
+    Py_CLEAR(self->dict);
+}
+
 static int
 ast_type_init(PyObject *self, PyObject *args, PyObject *kw)
 {
@@ -548,7 +554,7 @@
     "_ast.AST",
     sizeof(AST_object),
     0,
-    0,                       /* tp_dealloc */
+    (destructor)ast_dealloc, /* tp_dealloc */
     0,                       /* tp_print */
     0,                       /* tp_getattr */
     0,                       /* tp_setattr */