diff --git a/src/Helpers.php b/src/Helpers.php
index 7c4b042..5662ae4 100644
--- a/src/Helpers.php
+++ b/src/Helpers.php
@@ -48,7 +48,11 @@ public static function get_js_url( $local = false ) {
 	public static function get_filename() {
 		$client = static::get_client();
 
-		return $client->get_tracker_id();
+		if ( $client instanceof Client ) {
+			return $client->get_tracker_id();
+		}
+
+		return '';
 	}
 
 	/**