diff --git a/lib/ucoinpy/documents/__init__.py b/lib/ucoinpy/documents/__init__.py
index dcd251f8bb9e0d389c9ada9e97a98326c8127b56..54b24ddc14a370333240acf536a57b49cf777af3 100644
--- a/lib/ucoinpy/documents/__init__.py
+++ b/lib/ucoinpy/documents/__init__.py
@@ -24,7 +24,7 @@ class Document:
         '''
         self.signatures = []
         for k in keys:
-            self.signatures.append(k.sign(self.raw(), Base64Encoder))
+            self.signatures.append(k.signature(self.raw()))
 
     def signed_raw(self):
         '''
diff --git a/lib/ucoinpy/key/__init__.py b/lib/ucoinpy/key/__init__.py
index 45f8e8b63af52f20c8c5d912ea0538366a25bc9a..cb39fa374aa67c4cd06e110f16ddd1873370c4c7 100644
--- a/lib/ucoinpy/key/__init__.py
+++ b/lib/ucoinpy/key/__init__.py
@@ -27,7 +27,6 @@ class SigningKey(NaclSigningKey):
         super().__init__(seed)
         self.pubkey = Base58Encoder.encoder(self.vk)
 
-
 class Base58Encoder(object):
     @staticmethod
     def encode(data):