diff --git a/decouple.py b/decouple.py
index f499862..9873fc9 100644
--- a/decouple.py
+++ b/decouple.py
@@ -219,7 +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.
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)