diff --git a/wx/Help.php b/wx/Help.php
index b91d554..4075f31 100644
--- a/wx/Help.php
+++ b/wx/Help.php
@@ -6,7 +6,7 @@ namespace wchat;
 
 class Help extends Miniprogarampage
 {
-	
+
 	/**
 	 * @param array $data
 	 * @return string
@@ -74,16 +74,15 @@ class Help extends Miniprogarampage
 	public static function sign(array $array, $key, $type)
 	{
 		ksort($array, SORT_STRING);
-		$string = http_build_query($array);
-//		foreach ($array as $key => $val) {
-//			if (empty($string)) {
-//				$string = $key . '=' . $val;
-//			} else {
-//				$string .= '&' . $key . '=' . $val;
-//			}
-//		}
-		$string .= '&key=' . $key;
-
+		$string = [];
+		foreach ($array as $key => $val) {
+			if (empty($val)) {
+				continue;
+			}
+			$string[] = $key . '=' . $val;
+		}
+		$string[] = 'key=' . $key;
+		$string = implode('&', $string);
 		if ($type == 'MD5') {
 			return strtoupper(md5($string));
 		} else {