@@ -12,6 +12,9 @@ What's New in Python 3.3.3 release candidate 1?
 Core and Builtins
 -----------------
 
+- Issue #18552: Check return value of PyArena_AddPyObject() in
+  obj2ast_object().
+
 - Issue #18560: Fix potential NULL pointer dereference in sum().
 
 - Issue #15905: Fix theoretical buffer overflow in handling of sys.argv[0],
 
@@ -834,9 +834,13 @@ def visitModule(self, mod):
 {
     if (obj == Py_None)
         obj = NULL;
-    if (obj)
-        PyArena_AddPyObject(arena, obj);
-    Py_XINCREF(obj);
+    if (obj) {
+        if (PyArena_AddPyObject(arena, obj) < 0) {
+            *out = NULL;
+            return -1;
+        }
+        Py_INCREF(obj);
+    }
     *out = obj;
     return 0;
 }
 
@@ -688,9 +688,13 @@ static int obj2ast_object(PyObject* obj, PyObject** out, PyArena* arena)
 {
     if (obj == Py_None)
         obj = NULL;
-    if (obj)
-        PyArena_AddPyObject(arena, obj);
-    Py_XINCREF(obj);
+    if (obj) {
+        if (PyArena_AddPyObject(arena, obj) < 0) {
+            *out = NULL;
+            return -1;
+        }
+        Py_INCREF(obj);
+    }
     *out = obj;
     return 0;
 }