diff --git a/lib/tinkoff/request.rb b/lib/tinkoff/request.rb
index 605fee5..561fd3f 100644
--- a/lib/tinkoff/request.rb
+++ b/lib/tinkoff/request.rb
@@ -29,7 +29,7 @@ def prepare_params
     # Params signature
     def token
       values = @params.values.join
-      Digest::SHA256.digest(values)
+      Digest::SHA256.hexdigest(values)
     end
 
     def default_params