diff --git a/sys/compat/linux/linux_futex.c b/sys/compat/linux/linux_futex.c
index eb3ce342146..d16e047f831 100644
--- a/sys/compat/linux/linux_futex.c
+++ b/sys/compat/linux/linux_futex.c
@@ -931,7 +931,7 @@ linux_get_robust_list(struct thread *td, struct linux_get_robust_list_args *args
 	if (error != 0)
 		return (EFAULT);
 
-	return (copyout(&head, args->head, sizeof(head)));
+	return (copyout(&head, args->head, sizeof(l_uintptr_t)));
 }
 
 static int