diff --git a/AutoRest/Generators/Python/Python.Tests/AcceptanceTests/array_tests.py b/AutoRest/Generators/Python/Python.Tests/AcceptanceTests/array_tests.py
index 0b9a56ff2c9f8..c919eeb450ebe 100644
--- a/AutoRest/Generators/Python/Python.Tests/AcceptanceTests/array_tests.py
+++ b/AutoRest/Generators/Python/Python.Tests/AcceptanceTests/array_tests.py
@@ -208,7 +208,9 @@ def test_array(self):
         with self.assertRaises(DeserializationError):
             client.array.get_date_time_invalid_chars()
 
-        test_array = ['a string that gets encoded with base64url', 'test string', 'Lorem ipsum']
+        test_array = ['a string that gets encoded with base64url'.encode(),
+                      'test string'.encode(),
+                      'Lorem ipsum'.encode()]
         self.assertEqual(client.array.get_base64_url(), test_array)
 
 
diff --git a/AutoRest/Generators/Python/Python.Tests/AcceptanceTests/dictionary_tests.py b/AutoRest/Generators/Python/Python.Tests/AcceptanceTests/dictionary_tests.py
index a3dc4cef36f45..477591ffa9f4f 100644
--- a/AutoRest/Generators/Python/Python.Tests/AcceptanceTests/dictionary_tests.py
+++ b/AutoRest/Generators/Python/Python.Tests/AcceptanceTests/dictionary_tests.py
@@ -182,9 +182,9 @@ def test_dictionary_primitive_types(self):
         bytes_result = self.client.dictionary.get_byte_invalid_null()
         self.assertEqual(bytes_null, bytes_result)
 
-        test_dict = {'0': 'a string that gets encoded with base64url',
-                     '1': 'test string',
-                     '2': 'Lorem ipsum'}
+        test_dict = {'0': 'a string that gets encoded with base64url'.encode(),
+                     '1': 'test string'.encode(),
+                     '2': 'Lorem ipsum'.encode()}
         self.assertEqual(self.client.dictionary.get_base64_url(), test_dict)
 
     def test_basic_dictionary_parsing(self):
diff --git a/AutoRest/Generators/Python/Python.Tests/AcceptanceTests/string_tests.py b/AutoRest/Generators/Python/Python.Tests/AcceptanceTests/string_tests.py
index c012b3e9407cd..93c4d937535cc 100644
--- a/AutoRest/Generators/Python/Python.Tests/AcceptanceTests/string_tests.py
+++ b/AutoRest/Generators/Python/Python.Tests/AcceptanceTests/string_tests.py
@@ -104,10 +104,10 @@ def test_string(self):
         self.assertEqual(Colors.redcolor, client.enum.get_not_expandable())
         client.enum.put_not_expandable(Colors.redcolor)
 
-        self.assertEqual(client.string.get_base64_encoded(), 'a string that gets encoded with base64')
-        self.assertEqual(client.string.get_base64_url_encoded(), 'a string that gets encoded with base64url')
+        self.assertEqual(client.string.get_base64_encoded(), 'a string that gets encoded with base64'.encode())
+        self.assertEqual(client.string.get_base64_url_encoded(), 'a string that gets encoded with base64url'.encode())
         self.assertIsNone(client.string.get_null_base64_url_encoded())
-        client.string.put_base64_url_encoded('a string that gets encoded with base64url')
+        client.string.put_base64_url_encoded('a string that gets encoded with base64url'.encode())
 
 
 if __name__ == '__main__':
diff --git a/AutoRest/Generators/Python/Python.Tests/AcceptanceTests/url_tests.py b/AutoRest/Generators/Python/Python.Tests/AcceptanceTests/url_tests.py
index 9eee73e422f22..04e4c94e359a4 100644
--- a/AutoRest/Generators/Python/Python.Tests/AcceptanceTests/url_tests.py
+++ b/AutoRest/Generators/Python/Python.Tests/AcceptanceTests/url_tests.py
@@ -101,7 +101,7 @@ def test_url_path(self):
         with self.assertRaises(ValidationError):
             self.client.paths.enum_null(None)
 
-        self.client.paths.base64_url("lorem")
+        self.client.paths.base64_url("lorem".encode())
 
     def test_url_query(self):
 
diff --git a/ClientRuntimes/Python/msrest/msrest/serialization.py b/ClientRuntimes/Python/msrest/msrest/serialization.py
index ef16b011e4b7d..b2c7e67ca57ac 100644
--- a/ClientRuntimes/Python/msrest/msrest/serialization.py
+++ b/ClientRuntimes/Python/msrest/msrest/serialization.py
@@ -447,6 +447,10 @@ def serialize_unicode(self, data):
         :param data: Object to be serialized.
         :rtype: str
         """
+        try:
+            return data.value
+        except AttributeError:
+            pass
         try:
             if isinstance(data, unicode):
                 return data.encode(encoding='utf-8')
@@ -549,7 +553,7 @@ def serialize_base64(attr, **kwargs):
         :param attr: Object to be serialized.
         :rtype: str
         """
-        encoded = b64encode(attr.encode()).decode()
+        encoded = b64encode(attr).decode('ascii')
         return encoded.strip('=').replace('+', '-').replace('/', '_')
 
     @staticmethod
@@ -1005,11 +1009,10 @@ def deserialize_base64(attr):
         :rtype: bytearray
         :raises: TypeError if string format invalid.
         """
-        pad_count = 3 - (len(attr) + 3) % 4
-        padding = ['=']  * pad_count
-        attr = attr + ''.join(padding)
+        padding = '=' * (3 - (len(attr) + 3) % 4)
+        attr = attr + padding
         encoded = attr.replace('-', '+').replace('_', '/')
-        return b64decode(encoded).decode()
+        return b64decode(encoded)
 
     @staticmethod
     def deserialize_decimal(attr):