diff --git a/include/osmocom/abis/ipaccess.h b/include/osmocom/abis/ipaccess.h
index 1999fa4..7af882a 100644
--- a/include/osmocom/abis/ipaccess.h
+++ b/include/osmocom/abis/ipaccess.h
@@ -109,6 +109,6 @@
 };
 
 /* quick solution to get openBSC's ipaccess tools working. */
-int ipaccess_fd_cb(struct osmo_fd *bfd, unsigned int what);
+extern int ipaccess_fd_cb(struct osmo_fd *bfd, unsigned int what);
 
 #endif /* _OSMO_PROTO_IPACCESS_H */