diff --git a/dev/issue219_adaptertest.py b/dev/issue219_adaptertest.py
new file mode 100644
index 0000000..1d4394e
--- /dev/null
+++ b/dev/issue219_adaptertest.py
@@ -0,0 +1,124 @@
+#!/usr/bin/env python3
+
+from construct import (
+    Byte, Bytes, Checksum, Computed, Flag, GreedyBytes, GreedyString, If,
+    IfThenElse, Int32sl, Int32ul, Int64sl, Int64ul, Mapping, Padding, Peek,
+    Pointer, Prefixed, RepeatUntil, Struct, Switch, Tell, this,
+)
+from construct import Check, Int16ul, RawCopy, Switch, stream_write, ChecksumError, Adapter, Container, ListContainer
+from collections import OrderedDict
+from Cryptodome.Random import get_random_bytes
+
+class RandomBytes(Bytes):
+    """Same as Bytes, but generate random bytes when building"""
+
+    def _build(self, obj, stream, context, path):
+        print('generating random bytes...')
+        length = self.length(context) if callable(self.length) else self.length
+        data = get_random_bytes(length)
+        print('old:', sum(context.data))
+        print('new:', sum(data))
+        stream_write(stream, data, length, path)
+        return data
+
+# DynamicHeaderItem = Struct(
+#     "id" / Mapping(
+#         Byte,
+#         {
+#             'end': 0,
+#             'master_seed': 4,
+#         }
+#     ),
+#     "data" / Prefixed(
+#         Int32ul,
+#         Switch(
+#             this.id,
+#             {
+#                 'master_seed': RandomBytes(32),
+#             },
+#             default=GreedyBytes
+#         )
+#     )
+# )
+from pykeepass_issue219_deleteme import DynamicHeaderItem
+
+class DynamicDict(Adapter):
+    """ListContainer <---> Container
+    Convenience mapping so we dont have to iterate ListContainer to find
+    the right item
+
+    FIXME: lump kwarg was added to get around the fact that InnerHeader is
+    not truly a dict.  We lump all 'binary' InnerHeaderItems into a single list
+    """
+
+    def __init__(self, key, subcon, lump=[]):
+        super().__init__(subcon)
+        self.key = key
+        self.lump = lump
+
+    # map ListContainer to Container
+    def _decode(self, obj, context, path):
+        d = OrderedDict()
+        for l in self.lump:
+            d[l] = ListContainer([])
+        for item in obj:
+            if item[self.key] in self.lump:
+                d[item[self.key]].append(item)
+            else:
+                d[item[self.key]] = item
+
+        return Container(d)
+
+    # map Container to ListContainer
+    def _encode(self, obj, context, path):
+        l = []
+        for key in obj:
+            if key == 'master_seed':
+                print('key:', key, sum(obj[key].data))
+            if key in self.lump:
+                l += obj[key]
+            else:
+                l.append(obj[key])
+
+        return ListContainer(l)
+
+DynamicHeader4 = DynamicDict(
+    'id',
+    RepeatUntil(
+        lambda item, a, b: item.id == 'end',
+        DynamicHeaderItem
+    )
+)
+
+# master_seed header item
+master_dyn_item_data = (
+    # id, length
+    b'\x04' + b'\x20\x00\x00\x00' +
+    # seed
+    b'\xfe\xb9\xbecy\xd1\xe48\xf3\xf0T\xf5\x89\xa2(\xeeS\xd8\xd9BZ\t\xb7n\xc9j"\x12\xc3\x82\xd6\x83'
+)
+end_dyn_item_data = (
+    # id, length
+    b'\x00' + b'\x02\x00\x00\x00' +
+    # value
+    b'\r\n'
+)
+
+dynamic_dict = master_dyn_item_data + end_dyn_item_data
+
+if __name__ == '__main__':
+
+    print('PARSE')
+    header = DynamicHeader4.parse(dynamic_dict)
+    print('-------------------------------')
+    print('master_seed:', sum(header.master_seed.data))
+    print('-------------------------------')
+
+    print('BUILD')
+    header_data = DynamicHeader4.build(header)
+
+    print('PARSE')
+    header = DynamicHeader4.parse(header_data)
+    print('-------------------------------')
+    print('master_seed:', sum(header.master_seed.data))
+    print('-------------------------------')
\ No newline at end of file
diff --git a/dev/pykeepass_issue219_deleteme.py b/dev/pykeepass_issue219_deleteme.py
index ea38b04..7b70c17 100644
--- a/dev/pykeepass_issue219_deleteme.py
+++ b/dev/pykeepass_issue219_deleteme.py
@@ -5,10 +5,11 @@
     IfThenElse, Int32sl, Int32ul, Int64sl, Int64ul, Mapping, Padding, Peek,
     Pointer, Prefixed, RepeatUntil, Struct, Switch, Tell, this,
 )
-from construct import Check, Int16ul, RawCopy, Switch, stream_write, ChecksumError
+from construct import Check, Int16ul, RawCopy, Switch, stream_write, ChecksumError, Adapter, Container, ListContainer
+from collections import OrderedDict
 from Cryptodome.Random import get_random_bytes
 
-from pykeepass.kdbx_parsing.kdbx4 import compute_transformed, CompressionFlags, VariantDictionary, CipherId, DynamicDict
+from pykeepass.kdbx_parsing.kdbx4 import compute_transformed, CompressionFlags, VariantDictionary, CipherId
 from pykeepass.kdbx_parsing.common import compute_master
 import hmac
 import hashlib
@@ -81,6 +82,47 @@ def _build(self, obj, stream, context, path):
     )
 )
 
+
+class DynamicDict(Adapter):
+    """ListContainer <---> Container
+    Convenience mapping so we dont have to iterate ListContainer to find
+    the right item
+
+    FIXME: lump kwarg was added to get around the fact that InnerHeader is
+    not truly a dict.  We lump all 'binary' InnerHeaderItems into a single list
+    """
+
+    def __init__(self, key, subcon, lump=[]):
+        super().__init__(subcon)
+        self.key = key
+        self.lump = lump
+
+    # map ListContainer to Container
+    def _decode(self, obj, context, path):
+        d = OrderedDict()
+        for l in self.lump:
+            d[l] = ListContainer([])
+        for item in obj:
+            if item[self.key] in self.lump:
+                d[item[self.key]].append(item)
+            else:
+                d[item[self.key]] = item
+
+        return Container(d)
+
+    # map Container to ListContainer
+    def _encode(self, obj, context, path):
+        l = []
+        for key in obj:
+            if key == 'master_seed':
+                print('key:', key, sum(obj[key].data))
+            if key in self.lump:
+                l += obj[key]
+            else:
+                l.append(obj[key])
+
+        return ListContainer(l)
+
 DynamicHeader4 = DynamicDict(
     'id',
     RepeatUntil(
@@ -88,7 +130,7 @@ def _build(self, obj, stream, context, path):
         DynamicHeaderItem
     )
 )
-
+# from issue219_adaptertest_deleteme import DynamicHeader4
 
 Body4 = Struct(
     "transformed_key" / Computed(compute_transformed),
@@ -134,17 +176,18 @@ def _build(self, obj, stream, context, path):
     )
 )
 
-# parse the database
-opts = dict(password='password', keyfile='test4.key', decrypt=True, transformed_key=None)
-print('PARSING')
-parsed1 = KDBX.parse_file('test4.kdbx', **opts)
-# rebuild and try to reparse final result
-print('SAVING')
-del parsed1.header.data
-KDBX.build_file(parsed1, '/tmp/test4.kdbx', **opts)
-# parse the database
-print('PARSING')
-try:
-    parsed2 = KDBX.parse_file('/tmp/test4.kdbx', **opts)
-except ChecksumError:
-    pass
\ No newline at end of file
+if __name__ == '__main__':
+    # parse the database
+    opts = dict(password='password', keyfile='test4.key', decrypt=True, transformed_key=None)
+    print('PARSING')
+    parsed1 = KDBX.parse_file('test4.kdbx', **opts)
+    # rebuild and try to reparse final result
+    print('SAVING')
+    del parsed1.header.data
+    KDBX.build_file(parsed1, '/tmp/test4.kdbx', **opts)
+    # parse the database
+    print('PARSING')
+    try:
+        parsed2 = KDBX.parse_file('/tmp/test4.kdbx', **opts)
+    except ChecksumError:
+        pass
\ No newline at end of file