diff --git a/Objects/classobject.c b/Objects/classobject.c
index 79b0562..6d1f05c 100644
--- a/Objects/classobject.c
+++ b/Objects/classobject.c
@@ -1,6 +1,7 @@
 /* Class object implementation (dead now except for methods) */
 
 #include "Python.h"
+#include "pycore_object.h"
 #include "pycore_pymem.h"
 #include "pycore_pystate.h"
 #include "structmember.h"