diff --git a/CHANGELOG.md b/CHANGELOG.md
index fe44557..62e2163 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,11 @@
 Changelog
 =========
 
+3.7 (2023-01-09)
+----------------
+
+- Fix `Csv` cast hanging with `default=None`, now returning an empty list. (#149)
+
 3.6 (2022-02-02)
 ----------------
 
diff --git a/README.rst b/README.rst
index 6e36272..4184536 100644
--- a/README.rst
+++ b/README.rst
@@ -1,3 +1,4 @@
+========================================================
 Python Decouple: Strict separation of settings from code
 ========================================================
 
@@ -22,8 +23,6 @@ for separating settings from code.
     :target: https://pypi.python.org/pypi/python-decouple/
     :alt: Latest PyPI version
 
-
-
 .. contents:: Summary
 
 
@@ -42,6 +41,7 @@ The first 2 are *project settings* and the last 3 are *instance settings*.
 
 You should be able to change *instance settings* without redeploying your app.
 
+
 Why not just use environment variables?
 ---------------------------------------
 
@@ -61,6 +61,7 @@ Since it's a non-empty string, it will be evaluated as True.
 
 *Decouple* provides a solution that doesn't look like a workaround: ``config('DEBUG', cast=bool)``.
 
+
 Usage
 =====
 
@@ -88,8 +89,10 @@ Then use it on your ``settings.py``.
      EMAIL_HOST = config('EMAIL_HOST', default='localhost')
      EMAIL_PORT = config('EMAIL_PORT', default=25, cast=int)
 
+
 Encodings
 ---------
+
 Decouple's default encoding is `UTF-8`.
 
 But you can specify your preferred encoding.
@@ -112,11 +115,13 @@ If you wish to fall back to your system's default encoding use:
     config.encoding = locale.getpreferredencoding(False)
     SECRET_KEY = config('SECRET_KEY')
 
+
 Where is the settings data stored?
------------------------------------
+----------------------------------
 
 *Decouple* supports both *.ini* and *.env* files.
 
+
 Ini file
 ~~~~~~~~
 
@@ -134,6 +139,7 @@ Simply create a ``settings.ini`` next to your configuration module in the form:
 
 *Note*: Since ``ConfigParser`` supports *string interpolation*, to represent the character ``%`` you need to escape it as ``%%``.
 
+
 Env file
 ~~~~~~~~
 
@@ -148,6 +154,7 @@ Simply create a ``.env`` text file in your repository's root directory in the fo
     PERCENTILE=90%
     #COMMENTED=42
 
+
 Example: How do I use it with Django?
 -------------------------------------
 
@@ -191,6 +198,7 @@ and `dj-database-url <https://pypi.python.org/pypi/dj-database-url/>`_.
 
     # ...
 
+
 Attention with *undefined* parameters
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -201,6 +209,7 @@ If ``SECRET_KEY`` is not present in the ``.env``, *decouple* will raise an ``Und
 
 This *fail fast* policy helps you avoid chasing misbehaviours when you eventually forget a parameter.
 
+
 Overriding config files with environment variables
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -297,6 +306,7 @@ Let's see some examples for the above mentioned cases:
 
 As you can see, ``cast`` is very flexible. But the last example got a bit complex.
 
+
 Built in Csv Helper
 ~~~~~~~~~~~~~~~~~~~
 
@@ -340,6 +350,7 @@ By default *Csv* returns a ``list``, but you can get a ``tuple`` or whatever you
     >>> config('SECURE_PROXY_SSL_HEADER', cast=Csv(post_process=tuple))
     ('HTTP_X_FORWARDED_PROTO', 'https')
 
+
 Built in Choices helper
 ~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -383,6 +394,72 @@ You can also use a Django-like choices tuple:
     >>> config('CONNECTION_TYPE', cast=Choices(choices=CONNECTION_OPTIONS))
     'bluetooth'
 
+
+Frequently Asked Questions
+==========================
+
+
+1) How to specify the `.env` path?
+----------------------------------
+
+.. code-block:: python
+
+    import os
+    from decouple import Config, RepositoryEnv
+    
+    
+    config = Config(RepositoryEnv("path/to/.env"))
+
+
+2) How to use python-decouple with Jupyter?
+-------------------------------------------
+
+.. code-block:: python
+
+    import os
+    from decouple import Config, RepositoryEnv
+    
+    
+    config = Config(RepositoryEnv("path/to/.env"))
+
+
+3) How to specify a file with another name instead of `.env`?
+----------------------------------------------------------------
+
+.. code-block:: python
+
+    import os
+    from decouple import Config, RepositoryEnv
+    
+    
+    config = Config(RepositoryEnv("path/to/somefile-like-env"))
+
+
+4) How to define the path to my env file on a env var?
+--------------------------------------------------------
+
+.. code-block:: python
+
+    import os
+    from decouple import Config, RepositoryEnv
+    
+    
+    DOTENV_FILE = os.environ.get("DOTENV_FILE", ".env") # only place using os.environ
+    config = Config(RepositoryEnv(DOTENV_FILE))
+
+
+5) How can I have multiple *env* files working together?
+--------------------------------------------------------
+
+.. code-block:: python
+
+    from collections import ChainMap
+    from decouple import Config, RepositoryEnv
+    
+    
+    config = Config(ChainMap(RepositoryEnv(".private.env"), RepositoryEnv(".env")))
+
+
 Contribute
 ==========
 
diff --git a/decouple.py b/decouple.py
index b19ec86..9873fc9 100644
--- a/decouple.py
+++ b/decouple.py
@@ -11,10 +11,10 @@
 
 
 if PYVERSION >= (3, 0, 0):
-    from configparser import ConfigParser
+    from configparser import ConfigParser, NoOptionError
     text_type = str
 else:
-    from ConfigParser import SafeConfigParser as ConfigParser
+    from ConfigParser import SafeConfigParser as ConfigParser, NoOptionError
     text_type = unicode
 
 if PYVERSION >= (3, 2, 0):
@@ -134,7 +134,10 @@ def __contains__(self, key):
                 self.parser.has_option(self.SECTION, key))
 
     def __getitem__(self, key):
-        return self.parser.get(self.SECTION, key)
+        try:
+            return self.parser.get(self.SECTION, key)
+        except NoOptionError:
+            raise KeyError(key)
 
 
 class RepositoryEnv(RepositoryEmpty):
@@ -216,7 +219,7 @@ def _find_file(self, path):
 
         # search the parent
         parent = os.path.dirname(path)
-        if parent and parent != os.path.abspath(os.sep):
+        if parent and os.path.normcase(parent) != os.path.normcase(os.path.abspath(os.sep)):
             return self._find_file(parent)
 
         # reached root without finding any files.
@@ -271,6 +274,9 @@ def __init__(self, cast=text_type, delimiter=',', strip=string.whitespace, post_
 
     def __call__(self, value):
         """The actual transformation"""
+        if value is None:
+            return self.post_process()
+
         transform = lambda s: self.cast(s.strip(self.strip))
 
         splitter = shlex(value, posix=True)
diff --git a/setup.py b/setup.py
index e447851..e972783 100644
--- a/setup.py
+++ b/setup.py
@@ -6,7 +6,7 @@
 README = os.path.join(os.path.dirname(__file__), 'README.rst')
 
 setup(name='python-decouple',
-      version='3.6',
+      version='3.8',
       description='Strict separation of settings from code.',
       long_description=open(README).read(),
       author="Henrique Bastos", author_email="henrique@bastos.net",
diff --git a/tests/test_autoconfig.py b/tests/test_autoconfig.py
index 75d97c3..94af7cc 100644
--- a/tests/test_autoconfig.py
+++ b/tests/test_autoconfig.py
@@ -97,3 +97,13 @@ def test_autoconfig_env_default_encoding():
             assert config.encoding == DEFAULT_ENCODING
             assert 'ENV' == config('KEY', default='ENV')
             mopen.assert_called_once_with(filename, encoding=DEFAULT_ENCODING)
+
+
+def test_autoconfig_no_repository():
+    path = os.path.join(os.path.dirname(__file__), 'autoconfig', 'ini', 'no_repository')
+    config = AutoConfig(path)
+
+    with pytest.raises(UndefinedValueError):
+        config('KeyNotInEnvAndNotInRepository')
+
+    assert isinstance(config.config.repository, RepositoryEmpty)
diff --git a/tests/test_env.py b/tests/test_env.py
index a259af3..a91c95c 100644
--- a/tests/test_env.py
+++ b/tests/test_env.py
@@ -136,3 +136,7 @@ def test_env_with_quote(config):
     assert '"Y"' == config('KeyHasTwoDoubleQuote')
     assert '''"Y\'''' == config('KeyHasMixedQuotesAsData1')
     assert '''\'Y"''' == config('KeyHasMixedQuotesAsData2')
+
+def test_env_repo_keyerror(config):
+    with pytest.raises(KeyError):
+        config.repository['UndefinedKey']
diff --git a/tests/test_helper_csv.py b/tests/test_helper_csv.py
index 8d55a66..c5db287 100644
--- a/tests/test_helper_csv.py
+++ b/tests/test_helper_csv.py
@@ -29,3 +29,8 @@ def test_csv_quoted_parse():
     assert ['foo', "'bar, baz'", "'qux"] == csv(''' foo ,"'bar, baz'", "'qux"''')
 
     assert ['foo', '"bar, baz"', '"qux'] == csv(""" foo ,'"bar, baz"', '"qux'""")
+
+
+def test_csv_none():
+    csv = Csv()
+    assert [] == csv(None)
diff --git a/tests/test_ini.py b/tests/test_ini.py
index 6ff0523..f610078 100644
--- a/tests/test_ini.py
+++ b/tests/test_ini.py
@@ -121,3 +121,8 @@ def test_ini_undefined_but_present_in_os_environ(config):
 
 def test_ini_empty_string_means_false(config):
     assert False is config('KeyEmpty', cast=bool)
+
+
+def test_ini_repo_keyerror(config):
+    with pytest.raises(KeyError):
+        config.repository['UndefinedKey']
diff --git a/tests/test_secrets.py b/tests/test_secrets.py
index 481fdeb..7d6185b 100644
--- a/tests/test_secrets.py
+++ b/tests/test_secrets.py
@@ -1,5 +1,6 @@
 # coding: utf-8
 import os
+import pytest
 
 from decouple import Config, RepositorySecret
 
@@ -28,3 +29,10 @@ def test_secret_overriden_by_environ():
     os.environ['db_user'] = 'hi'
     assert 'hi' == config('db_user')
     del os.environ['db_user']
+
+def test_secret_repo_keyerror():
+    path = os.path.join(os.path.dirname(__file__), 'secrets')
+    repo = RepositorySecret(path)
+
+    with pytest.raises(KeyError):
+        repo['UndefinedKey']