diff --git a/lemmy-docker.nix b/lemmy-docker.nix
index f087e14..3327220 100644
--- a/lemmy-docker.nix
+++ b/lemmy-docker.nix
@@ -18,7 +18,7 @@ let
         proxy = {
           service = {
             image = proxyCfg.image;
-            ports = [ "${port}:8536" ];
+            ports = [ "${toString port}:8536" ];
             volumes = [ "${proxyCfg.configFile}:/etc/nginx/nginx.conf:ro,Z" ];
             depends_on = [ "pictrs" "lemmy-ui" ];
           };