diff --git a/wp-includes/http.php b/wp-includes/http.php
index 351eef24f..e12fd0279 100644
--- a/wp-includes/http.php
+++ b/wp-includes/http.php
@@ -281,7 +281,10 @@ class WP_Http {
 			$transports = WP_Http::_getTransport($r);
 		} else {
 			if ( is_array( $r['body'] ) || is_object( $r['body'] ) ) {
-				$r['body'] = http_build_query($r['body'], null, '&');
+				if ( ! version_compare(phpversion(), '5.1.2', '>=') ) 
+					$r['body'] = _http_build_query($r['body'], null, '&');
+				else
+					$r['body'] = http_build_query($r['body'], null, '&');
 				$r['headers']['Content-Type'] = 'application/x-www-form-urlencoded; charset=' . get_option('blog_charset');
 				$r['headers']['Content-Length'] = strlen($r['body']);
 			}