use NULL for the ends of tables
diff --git a/Modules/_io/iobase.c b/Modules/_io/iobase.c
index ef6d516..5e018da 100644
--- a/Modules/_io/iobase.c
+++ b/Modules/_io/iobase.c
@@ -700,7 +700,7 @@
 
 static PyGetSetDef IOBase_getset[] = {
     {"closed", (getter)IOBase_closed_get, NULL, NULL},
-    {0}
+    {NULL}
 };