diff --git a/tests/unit/providers/test_configuration_py2_py3.py b/tests/unit/providers/test_configuration_py2_py3.py
index 3cf42102..f6cde39d 100644
--- a/tests/unit/providers/test_configuration_py2_py3.py
+++ b/tests/unit/providers/test_configuration_py2_py3.py
@@ -591,17 +591,20 @@ class ConfigFromIniWithEnvInterpolationTests(unittest.TestCase):
         self.config = providers.Configuration(name='config')
 
         os.environ['CONFIG_TEST_ENV'] = 'test-value'
+        os.environ['CONFIG_TEST_PATH'] = 'test-path'
 
         _, self.config_file = tempfile.mkstemp()
         with open(self.config_file, 'w') as config_file:
             config_file.write(
                 '[section1]\n'
                 'value1=${CONFIG_TEST_ENV}\n'
+                'value2=${CONFIG_TEST_PATH}/path\n'
             )
 
     def tearDown(self):
         del self.config
-        del os.environ['CONFIG_TEST_ENV']
+        os.environ.pop('CONFIG_TEST_ENV', None)
+        os.environ.pop('CONFIG_TEST_PATH', None)
         os.unlink(self.config_file)
 
     def test_env_variable_interpolation(self):
@@ -612,11 +615,44 @@ class ConfigFromIniWithEnvInterpolationTests(unittest.TestCase):
             {
                 'section1': {
                     'value1': 'test-value',
+                    'value2': 'test-path/path',
                 },
             },
         )
-        self.assertEqual(self.config.section1(), {'value1': 'test-value'})
+        self.assertEqual(
+            self.config.section1(),
+            {
+                'value1': 'test-value',
+                'value2': 'test-path/path',
+            },
+        )
         self.assertEqual(self.config.section1.value1(), 'test-value')
+        self.assertEqual(self.config.section1.value2(), 'test-path/path')
+
+    def test_missing_envs(self):
+        del os.environ['CONFIG_TEST_ENV']
+        del os.environ['CONFIG_TEST_PATH']
+
+        self.config.from_ini(self.config_file)
+
+        self.assertEqual(
+            self.config(),
+            {
+                'section1': {
+                    'value1': '${CONFIG_TEST_ENV}',
+                    'value2': '${CONFIG_TEST_PATH}/path',
+                },
+            },
+        )
+        self.assertEqual(
+            self.config.section1(),
+            {
+                'value1': '${CONFIG_TEST_ENV}',
+                'value2': '${CONFIG_TEST_PATH}/path',
+            },
+        )
+        self.assertEqual(self.config.section1.value1(), '${CONFIG_TEST_ENV}')
+        self.assertEqual(self.config.section1.value2(), '${CONFIG_TEST_PATH}/path')
 
 
 class ConfigFromYamlTests(unittest.TestCase):
@@ -793,8 +829,8 @@ class ConfigFromYamlWithEnvInterpolationTests(unittest.TestCase):
 
     def tearDown(self):
         del self.config
-        del os.environ['CONFIG_TEST_ENV']
-        del os.environ['CONFIG_TEST_PATH']
+        os.environ.pop('CONFIG_TEST_ENV', None)
+        os.environ.pop('CONFIG_TEST_PATH', None)
         os.unlink(self.config_file)
 
     @unittest.skipIf(sys.version_info[:2] == (3, 4), 'PyYAML does not support Python 3.4')
@@ -820,6 +856,32 @@ class ConfigFromYamlWithEnvInterpolationTests(unittest.TestCase):
         self.assertEqual(self.config.section1.value1(), 'test-value')
         self.assertEqual(self.config.section1.value2(), 'test-path/path')
 
+    @unittest.skipIf(sys.version_info[:2] == (3, 4), 'PyYAML does not support Python 3.4')
+    def test_missing_envs(self):
+        del os.environ['CONFIG_TEST_ENV']
+        del os.environ['CONFIG_TEST_PATH']
+
+        self.config.from_yaml(self.config_file)
+
+        self.assertEqual(
+            self.config(),
+            {
+                'section1': {
+                    'value1': '${CONFIG_TEST_ENV}',
+                    'value2': '${CONFIG_TEST_PATH}/path',
+                },
+            },
+        )
+        self.assertEqual(
+            self.config.section1(),
+            {
+                'value1': '${CONFIG_TEST_ENV}',
+                'value2': '${CONFIG_TEST_PATH}/path',
+            },
+        )
+        self.assertEqual(self.config.section1.value1(), '${CONFIG_TEST_ENV}')
+        self.assertEqual(self.config.section1.value2(), '${CONFIG_TEST_PATH}/path')
+
     @unittest.skipIf(sys.version_info[:2] == (3, 4), 'PyYAML does not support Python 3.4')
     def test_option_env_variable_interpolation(self):
         self.config.option.from_yaml(self.config_file)