diff --git a/services/redis.nix b/services/redis.nix
index f557c31..690522d 100644
--- a/services/redis.nix
+++ b/services/redis.nix
@@ -19,7 +19,7 @@ let
   generateRedisConfig = ''
     cat > $RUNTIME_PATH/${name}.conf <<EOF
     ${lib.optionalString default_config ''
-      port ${port}
+      port ${builtins.toString port}
       ${lib.optionalString (bind != null) "bind ${bind}"}
       ${lib.optionalString (port == 0) "unixsocket $RUNTIME_PATH/${name}.sock"}
       ${lib.optionalString (port == 0) "unixsocketperm 700"}