diff --git a/tests/utils_tests.py b/tests/utils_tests.py
new file mode 100644
index 0000000..d7edd0e
--- /dev/null
+++ b/tests/utils_tests.py
@@ -0,0 +1,122 @@
+import datetime
+import unittest
+import uuid
+
+import arrow
+
+from sprockets.clients.dynamodb import utils
+
+
+class UTC(datetime.tzinfo):
+    def utcoffset(self, dt):
+        return datetime.timedelta(0)
+
+    def tzname(self, dt):
+        return 'UTC'
+
+    def dst(self, dt):
+        return datetime.timedelta(0)
+
+
+class MarshallTests(unittest.TestCase):
+    maxDiff = None
+
+    def test_complex_document(self):
+        uuid_value = uuid.uuid4()
+        arrow_value = arrow.utcnow()
+        dt_value = datetime.datetime.utcnow().replace(tzinfo=UTC())
+        value = {
+            'key1': 'str',
+            'key2': 10,
+            'key3': {
+                'sub-key1': 20,
+                'sub-key2': True,
+                'sub-key3': 'value'
+            },
+            'key4': None,
+            'key5': ['one', 'two', 'three', 4, None, True],
+            'key6': set(['a', 'b', 'c']),
+            'key7': {1, 2, 3, 4},
+            'key8': arrow_value,
+            'key9': uuid_value,
+            'key10': b'\0x01\0x02\0x03',
+            'key11': {b'\0x01\0x02\0x03', b'\0x04\0x05\0x06'},
+            'key12': dt_value
+        }
+        expectation = {
+            'key1': {'S': 'str'},
+            'key2': {'N': '10'},
+            'key3': {'M':
+                {
+                    'sub-key1': {'N': '20'},
+                    'sub-key2': {'BOOL': True},
+                    'sub-key3': {'S': 'value'}
+                }
+            },
+            'key4': {'NULL': True},
+            'key5': {'L': [{'S': 'one'}, {'S': 'two'}, {'S': 'three'},
+                           {'N': '4'}, {'NULL': True}, {'BOOL': True}]},
+            'key6': {'SS': ['a', 'b', 'c']},
+            'key7': {'NS': ['1', '2', '3', '4']},
+            'key8': {'S': arrow_value.isoformat()},
+            'key9': {'S': str(uuid_value)},
+            'key10': {'B': b'\0x01\0x02\0x03'},
+            'key11': {'BS': [b'\0x01\0x02\0x03', b'\0x04\0x05\0x06']},
+            'key12': {'S': dt_value.isoformat()}
+        }
+        self.assertDictEqual(expectation, utils.marshall(value))
+
+    def test_value_error_raised_on_unsupported_type(self):
+        self.assertRaises(ValueError, utils.marshall, {'key': self})
+
+    def test_value_error_raised_on_mixed_set(self):
+        self.assertRaises(ValueError, utils.marshall, {'key': {1, 'two', 3}})
+
+
+class UnmarshallTests(unittest.TestCase):
+    maxDiff = None
+
+    def test_complex_document(self):
+        uuid_value = uuid.uuid4()
+        dt_value = arrow.utcnow()
+        value = {
+            'key1': {'S': 'str'},
+            'key2': {'N': '10'},
+            'key3': {'M':
+                {
+                    'sub-key1': {'N': '20'},
+                    'sub-key2': {'BOOL': True},
+                    'sub-key3': {'S': 'value'}
+                }
+            },
+            'key4': {'NULL': True},
+            'key5': {'L': [{'S': 'one'}, {'S': 'two'}, {'S': 'three'},
+                           {'N': '4'}, {'NULL': True}, {'BOOL': True}]},
+            'key6': {'SS': ['a', 'b', 'c']},
+            'key7': {'NS': ['1', '2', '3', '4']},
+            'key8': {'S': dt_value.isoformat()},
+            'key9': {'S': str(uuid_value)},
+            'key10': {'B': b'\0x01\0x02\0x03'},
+            'key11': {'BS': [b'\0x01\0x02\0x03', b'\0x04\0x05\0x06']}
+        }
+        expectation = {
+            'key1': 'str',
+            'key2': 10,
+            'key3': {
+                'sub-key1': 20,
+                'sub-key2': True,
+                'sub-key3': 'value'
+            },
+            'key4': None,
+            'key5': ['one', 'two', 'three', 4, None, True],
+            'key6': {'a', 'b', 'c'},
+            'key7': {1, 2, 3, 4},
+            'key8': dt_value.isoformat(),
+            'key9': uuid_value,
+            'key10': b'\0x01\0x02\0x03',
+            'key11': {b'\0x01\0x02\0x03', b'\0x04\0x05\0x06'}
+        }
+        self.assertDictEqual(expectation, utils.unmarshall(value))
+
+    def test_value_error_raised_on_unsupported_type(self):
+        self.assertRaises(ValueError, utils.unmarshall, {'key': {'T': 1}})