diff --git a/cryptoconditions/types/preimage.py b/cryptoconditions/types/preimage.py
index b5b568b..956bb48 100644
--- a/cryptoconditions/types/preimage.py
+++ b/cryptoconditions/types/preimage.py
@@ -15,7 +15,7 @@ class PreimageSha256(BaseSha256):
     TYPE_ASN1_FULFILLMENT = 'preimageSha256Fulfillment'
     TYPE_CATEGORY = 'simple'
 
-    def __init__(self, preimage=None, asn1=None):
+    def __init__(self, preimage=None):
         """
         PREIMAGE-SHA-256: Hashlock condition using SHA-256.
 
@@ -43,62 +43,6 @@ def __init__(self, preimage=None, asn1=None):
         if preimage and (not isinstance(preimage, bytes)):
             raise TypeError('Preimage must be bytes, was: {}'.format(preimage))
         self.preimage = preimage
-        self.asn1 = asn1
-
-    @property
-    def bitmask(self):
-        return self.FEATURE_BITMASK
-
-    #def write_hash_payload(self, hasher):
-    #    """
-    #    Generate the contents of the condition hash.
-
-    #    Writes the contents of the condition hash to a Hasher. Used internally by `getCondition`.
-
-    #    HASH = SHA256(PREIMAGE)
-
-    #    Args:
-    #         hasher (Hasher): Destination where the hash payload will be written.
-    #    """
-    #    if not isinstance(hasher, Hasher):
-    #        raise TypeError('hasher must be a Hasher instance')
-    #    if self.preimage is None:
-    #        raise ValueError('Could not calculate hash, no preimage provided')
-    #    hasher.write(self.preimage)
-
-    #def parse_payload(self, reader, payload_size):
-    #    """
-    #    Parse the payload of a SHA256 hashlock fulfillment.
-
-    #    Read a fulfillment payload from a Reader and populate this object with that fulfillment.
-
-    #    FULFILLMENT_PAYLOAD =
-    #        VARBYTES PREIMAGE
-
-    #    Args:
-    #        reader (Reader): Source to read the fulfillment payload from.
-    #        payload_size (int): Total size of the fulfillment payload.
-    #    """
-    #    if not isinstance(reader, Reader):
-    #        raise TypeError('reader must be a Reader instance')
-    #    self.preimage = reader.read(payload_size)
-
-    #def write_payload(self, writer):
-    #    """
-    #    Generate the fulfillment payload.
-
-    #    This writes the fulfillment payload to a Writer.
-
-    #    Args:
-    #        writer (Writer): Subject for writing the fulfillment payload.
-    #    """
-    #    if not isinstance(writer, (Writer, Predictor)):
-    #        raise TypeError('writer must be a Writer instance')
-    #    if self.preimage is None:
-    #        raise ValueError('Preimage must be specified')
-
-    #    writer.write(self.preimage)
-    #    return writer
 
     def to_dict(self):
         """
@@ -110,7 +54,6 @@ def to_dict(self):
         return {
             'type': 'fulfillment',
             'type_id': self.TYPE_ID,
-            'bitmask': self.bitmask,
             'preimage': self.preimage.decode()
         }
 
@@ -124,8 +67,8 @@ def to_asn1_dict(self):
     @property
     def fingerprint_contents(self):
         if self.preimage is None:
-            # TODO MissingDataError('Could not calculate hash, no preimage provided')
-            raise Exception('Could not calculate hash, no preimage provided')
+            raise MissingDataError(
+                'Could not calculate hash, no preimage provided')
         return self.preimage
 
     def parse_json(self, data):