--- a/server/iface.c	2003-07-19 15:02:43.000000000 +0200
+++ b/server/iface.c	2026-10-16 22:08:21.380448646 +0200
@@ -2,7 +2,9 @@
 #include <string.h>
 #include <net/if.h>
 #include <sys/ioctl.h>
+#if __has_include(<linux/isdn.h>)
 #include <linux/isdn.h>
+#endif
 #include <syslog.h>
 #include <stdlib.h>