diff --git a/Package.swift b/Package.swift
index 5d15a1b0d..044358375 100644
--- a/Package.swift
+++ b/Package.swift
@@ -1,4 +1,4 @@
-// swift-tools-version:5.3
+// swift-tools-version:5.9
 // The swift-tools-version declares the minimum version of Swift required to build this package.
 
 import PackageDescription
diff --git a/Sources/WireGuardKitC/WireGuardKitC.h b/Sources/WireGuardKitC/WireGuardKitC.h
index 54e4783d4..3854241c4 100644
--- a/Sources/WireGuardKitC/WireGuardKitC.h
+++ b/Sources/WireGuardKitC/WireGuardKitC.h
@@ -1,20 +1,22 @@
 // SPDX-License-Identifier: MIT
 // Copyright © 2018-2023 WireGuard LLC. All Rights Reserved.
 
+#include <stdint.h>
+
 #include "key.h"
 #include "x25519.h"
 
 /* From <sys/kern_control.h> */
 #define CTLIOCGINFO 0xc0644e03UL
 struct ctl_info {
-    u_int32_t   ctl_id;
+    uint32_t    ctl_id;
     char        ctl_name[96];
 };
 struct sockaddr_ctl {
-    u_char      sc_len;
-    u_char      sc_family;
-    u_int16_t   ss_sysaddr;
-    u_int32_t   sc_id;
-    u_int32_t   sc_unit;
-    u_int32_t   sc_reserved[5];
+    uint8_t     sc_len;
+    uint8_t     sc_family;
+    uint16_t    ss_sysaddr;
+    uint32_t    sc_id;
+    uint32_t    sc_unit;
+    uint32_t    sc_reserved[5];
 };