diff --git a/src/rpcclient/rpcclient/darwin/structs.py b/src/rpcclient/rpcclient/darwin/structs.py
index 5728e61..b69740f 100644
--- a/src/rpcclient/rpcclient/darwin/structs.py
+++ b/src/rpcclient/rpcclient/darwin/structs.py
@@ -27,7 +27,6 @@
 blksize_t = Int32ul
 ino64_t = Int64ul
 fsid_t = Array(2, Int32sl)
-mach_port_t = Int64ul
 io_name_t = PaddedString(1024, 'utf8')
 io_object_t = Int64ul
 vm_prot_t = Int32ul
@@ -41,6 +40,7 @@
 natural_t = Int32ul
 mach_port_name_t = natural_t
 integer_t = Int32sl
+mach_port_t = natural_t
 mach_port_type_t = natural_t
 mach_port_urefs_t = natural_t