diff --git a/src/Handlers/HMAC/Hmac.php b/src/Handlers/HMAC/Hmac.php
index 0ef34533..5b3befb6 100644
--- a/src/Handlers/HMAC/Hmac.php
+++ b/src/Handlers/HMAC/Hmac.php
@@ -50,7 +50,11 @@ public function base64Data($data = null)
         {
             if (is_array($data))
             {
-                $data = json_encode($data, JSON_UNESCAPED_UNICODE | JSON_PRESERVE_ZERO_FRACTION);
+                $data = mb_convert_encoding(
+                    json_encode($data, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE),
+                    'UTF-8',
+                    'auto'
+                );
             }
 
             $md5 = md5($data, true);