--- /dev/null
+--- bird-1.6.8/sysdep/unix/krt.h~ 2019-08-12 14:59:56.000000000 +0200
++++ bird-1.6.8/sysdep/unix/krt.h 2020-11-27 12:58:28.686870081 +0100
+@@ -112,7 +112,7 @@ struct kif_proto {
+ struct kif_state sys; /* Sysdep state */
+ };
+
+-struct kif_proto *kif_proto;
++extern struct kif_proto *kif_proto;
+
+ #define KIF_CF ((struct kif_config *)p->p.cf)
+