diff --git a/S3.php b/S3.php
index eedf1853..04f11ff2 100644
--- a/S3.php
+++ b/S3.php
@@ -2012,7 +2012,7 @@ public static function __getSignatureV4($amzHeaders, $headers, $method, $uri, $p
 		// Convert null query string parameters to strings and sort
 		$parameters = array_map('strval', $parameters); 
 		uksort($parameters, array('self', '__sortMetaHeadersCmp'));
-		$queryString = http_build_query($parameters, null, '&', PHP_QUERY_RFC3986);
+		$queryString = http_build_query($parameters, '' /* $numeric_prefix */, '&', PHP_QUERY_RFC3986);
 
 		// Payload
 		$amzPayload = array($method);