--- src/openconnect-internal.h      2024-01-29 10:46:51.790424618 +0000
+++ src/openconnect-internal.h      2024-01-29 10:46:51.774424617 +0000
@@ -167,6 +167,7 @@
 #ifdef HAVE_VHOST
 #include <linux/virtio_net.h>
 #include <linux/vhost.h>
+#include <stdlib.h>
 
 struct oc_vring {
        struct vring_desc *desc;