diff --git a/default.nginx.conf b/default.nginx.conf
index cbdd230..9b2ae66 100644
--- a/default.nginx.conf
+++ b/default.nginx.conf
@@ -6,8 +6,11 @@ events {}
 
 stream {
     server {
-        set_by_lua $nginx_proxy_source_port 'return os.getenv("$NGINX_PROXY_SOURCE_PORT")';
-        set_by_lua $nginx_proxy_source_address 'return os.getenv("$NGINX_PROXY_SOURCE_ADDRESS")';
+        set_by_lua_block {
+             ngx.var.nginx_proxy_source_port = os.getenv("$NGINX_PROXY_SOURCE_PORT");
+             ngx.var.nginx_proxy_source_address = os.getenv("$NGINX_PROXY_SOURCE_ADDRESS");
+        }
+
         listen $nginx_proxy_source_port;
         proxy_pass $nginx_proxy_source_address;
     }