diff --git a/mifiel/document.py b/mifiel/document.py
index 783e274..fa97039 100644
--- a/mifiel/document.py
+++ b/mifiel/document.py
@@ -43,9 +43,15 @@ def create(client, signatories, **kwargs):
     data = kwargs.copy()
     for index, item in enumerate(signatories):
       for key, val in item.items():
-        data.update(
-          {'signatories[' + str(index) + '][' + str(key) + ']': val}
-        )
+        if key == 'allowed_signature_methods' and isinstance(val, list):
+          for method in val:
+            data.append(
+              (f'signatories[{index}][{key}][]', method)
+            )
+        else:
+            data.append(
+              (f'signatories[{index}][{key}]', val)
+            )
 
     if 'viewers' in data:
       viewers = data.pop('viewers')