Fixed a pair of typos in docstrings
diff --git a/acme/acme/jose/json_util.py b/acme/acme/jose/json_util.py
index 7b95e3fce4d..977a0662266 100644
--- a/acme/acme/jose/json_util.py
+++ b/acme/acme/jose/json_util.py
@@ -226,7 +226,7 @@ def encode(self, name):
 
         :param str name: Name of the field to be encoded.
 
-        :raises erors.SerializationError: if field cannot be serialized
+        :raises errors.SerializationError: if field cannot be serialized
         :raises errors.Error: if field could not be found
 
         """
diff --git a/acme/acme/jose/util.py b/acme/acme/jose/util.py
index ab3606efc8a..600077b2016 100644
--- a/acme/acme/jose/util.py
+++ b/acme/acme/jose/util.py
@@ -130,7 +130,7 @@ class ImmutableMap(collections.Mapping, collections.Hashable):
     """Immutable key to value mapping with attribute access."""
 
     __slots__ = ()
-    """Must be overriden in subclasses."""
+    """Must be overridden in subclasses."""
 
     def __init__(self, **kwargs):
         if set(kwargs) != set(self.__slots__):
