diff --git a/acme/acme/fields.py b/acme/acme/fields.py
index 15a5b0add..7ecaa908e 100644
--- a/acme/acme/fields.py
+++ b/acme/acme/fields.py
@@ -56,8 +56,8 @@ class Resource(jose.Field):
 
     def __init__(self, resource_type: str, *args: Any, **kwargs: Any) -> None:
         self.resource_type = resource_type
-        super().__init__(
-            'resource', default=resource_type, *args, **kwargs)  # type: ignore[misc]
+        kwargs['default'] = resource_type
+        super().__init__('resource', *args, **kwargs)
 
     def decode(self, value: Any) -> Any:
         if value != self.resource_type:
diff --git a/acme/acme/jws.py b/acme/acme/jws.py
index ea48ab380..2978f006a 100644
--- a/acme/acme/jws.py
+++ b/acme/acme/jws.py
@@ -14,7 +14,7 @@ class Header(jose.Header):
     """
     nonce: bytes = jose.field('nonce', omitempty=True, encoder=jose.encode_b64jose)
     kid: bytes = jose.field('kid', omitempty=True)
-    url: str = jose.field('url', omitempty=True)
+    url: bytes = jose.field('url', omitempty=True)
 
     # Mypy does not understand the josepy magic happening here, and falsely claims
     # that nonce is redefined. Let's ignore the type check here.