diff --git a/Sources/WireGuardKitC/WireGuardKitC.h b/Sources/WireGuardKitC/WireGuardKitC.h
index 54e4783d4..84c53f706 100644
--- a/Sources/WireGuardKitC/WireGuardKitC.h
+++ b/Sources/WireGuardKitC/WireGuardKitC.h
@@ -1,6 +1,8 @@
 // SPDX-License-Identifier: MIT
 // Copyright © 2018-2023 WireGuard LLC. All Rights Reserved.
 
+#include <sys/types.h>
+
 #include "key.h"
 #include "x25519.h"