diff --git a/Modules/sha512module.c b/Modules/sha512module.c
index 5ac2a2a..d8c846a 100644
--- a/Modules/sha512module.c
+++ b/Modules/sha512module.c
@@ -594,7 +594,7 @@
 static PyTypeObject SHA384type = {
     PyVarObject_HEAD_INIT(NULL, 0)
     "_sha512.sha384",   /*tp_name*/
-    sizeof(SHAobject),  /*tp_size*/
+    sizeof(SHAobject),  /*tp_basicsize*/
     0,                  /*tp_itemsize*/
     /* methods */
     SHA512_dealloc,     /*tp_dealloc*/
@@ -628,7 +628,7 @@
 static PyTypeObject SHA512type = {
     PyVarObject_HEAD_INIT(NULL, 0)
     "_sha512.sha512",   /*tp_name*/
-    sizeof(SHAobject),  /*tp_size*/
+    sizeof(SHAobject),  /*tp_basicsize*/
     0,                  /*tp_itemsize*/
     /* methods */
     SHA512_dealloc,     /*tp_dealloc*/