diff --git a/ngx-http-concat.php b/ngx-http-concat.php
index c9f01fa..f105ab2 100644
--- a/ngx-http-concat.php
+++ b/ngx-http-concat.php
@@ -94,12 +94,10 @@ function concat_get_path( $uri ) {
 
 $args = rawurldecode( $args );
 
-if ( false === strpos( $args, '?' ) ) {
-	concat_http_status_exit( 400 );
+if ( 0 === strpos( $args, '?' ) ) {
+	$args = ltrim( $args, '?' );
 }
 
-$args = substr( $args, strpos( $args, '?' ) + 1 );
-
 // /foo/bar.css,/foo1/bar/baz.css?m=293847g
 // or
 // -eJzTT8vP109KLNJLLi7W0QdyDEE8IK4CiVjn2hpZGluYmKcDABRMDPM=