diff --git a/nix/nixos-module/container/bird.nix b/nix/nixos-module/container/bird.nix
index 318dab3..26703c4 100644
--- a/nix/nixos-module/container/bird.nix
+++ b/nix/nixos-module/container/bird.nix
@@ -8,7 +8,7 @@ let
     upstream != null
   ) hostConf.interfaces;
 
-  isUpstream = upstreamInterfaces != [];
+  isUpstream = upstreamInterfaces != {};
 
   # Configuring a gateway? If so, this is the associated net.
   gatewayNet =