diff --git a/nix/nixos-module/container/bird.nix b/nix/nixos-module/container/bird.nix
index 718e202..bd50912 100644
--- a/nix/nixos-module/container/bird.nix
+++ b/nix/nixos-module/container/bird.nix
@@ -256,7 +256,7 @@ in
 
         ${lib.concatMapStrings ({ n, x }: let upstream = x; in ''
           # upstream client instance #${toString n}
-          protocol bgp bgp_up_${upstream} {
+          protocol bgp bgp_up_${builtins.replaceStrings ["-"] ["_"] upstream} {
             local as ${toString hostConf.bgp.asn};
             neighbor ${config.site.net.core.hosts6.dn42.${upstream}} as ${toString hostConf.bgp.asn};
             direct;