diff --git a/tests/unit/test_vcr.py b/tests/unit/test_vcr.py
index 1029de6..cbdcde4 100644
--- a/tests/unit/test_vcr.py
+++ b/tests/unit/test_vcr.py
@@ -72,6 +72,32 @@ def test_vcr_before_record_request_params():
         assert cassette.filter_request(Request('GET', base_path + 'get', '', {})) is not None
 
 
+def test_vcr_before_record_response_iterable():
+    # Regression test for #191
+
+    request = Request('GET', '/', '', {})
+    response = object()  # just can't be None
+
+    # Prevent actually saving the cassette
+    with mock.patch('vcr.cassette.save_cassette'):
+
+        # Baseline: non-iterable before_record_response should work
+        mock_filter = mock.Mock()
+        vcr = VCR(before_record_response=mock_filter)
+        with vcr.use_cassette('test') as cassette:
+            assert mock_filter.call_count == 0
+            cassette.append(request, response)
+            assert mock_filter.call_count == 1
+
+        # Regression test: iterable before_record_response should work too
+        mock_filter = mock.Mock()
+        vcr = VCR(before_record_response=(mock_filter,))
+        with vcr.use_cassette('test') as cassette:
+            assert mock_filter.call_count == 0
+            cassette.append(request, response)
+            assert mock_filter.call_count == 1
+
+
 @pytest.fixture
 def random_fixture():
     return 1
diff --git a/vcr/cassette.py b/vcr/cassette.py
index ff63492..bc7410f 100644
--- a/vcr/cassette.py
+++ b/vcr/cassette.py
@@ -164,7 +164,7 @@ class Cassette(object):
         return CassetteContextDecorator.from_args(cls, **kwargs)
 
     def __init__(self, path, serializer=yamlserializer, record_mode='once',
-                 match_on=(uri, method),  before_record_request=None,
+                 match_on=(uri, method), before_record_request=None,
                  before_record_response=None, custom_patches=(),
                  inject=False):
 
@@ -210,8 +210,7 @@ class Cassette(object):
         request = self._before_record_request(request)
         if not request:
             return
-        if self._before_record_response:
-            response = self._before_record_response(response)
+        response = self._before_record_response(response)
         self.data.append((request, response))
         self.dirty = True
 
diff --git a/vcr/config.py b/vcr/config.py
index 0c45844..a94520f 100644
--- a/vcr/config.py
+++ b/vcr/config.py
@@ -67,10 +67,11 @@ class VCR(object):
         try:
             serializer = self.serializers[serializer_name]
         except KeyError:
-            print("Serializer {0} doesn't exist or isn't registered".format(
-                serializer_name
-            ))
-            raise KeyError
+            raise KeyError(
+                "Serializer {0} doesn't exist or isn't registered".format(
+                    serializer_name
+                )
+            )
         return serializer
 
     def _get_matchers(self, matcher_names):
@@ -157,12 +158,10 @@ class VCR(object):
             'before_record_response', self.before_record_response
         )
         filter_functions = []
-        if before_record_response and not isinstance(before_record_response,
-                                                     collections.Iterable):
-            before_record_response = (before_record_response,)
-            for function in before_record_response:
-                filter_functions.append(function)
-
+        if before_record_response:
+            if not isinstance(before_record_response, collections.Iterable):
+                before_record_response = (before_record_response,)
+            filter_functions.extend(before_record_response)
         def before_record_response(response):
             for function in filter_functions:
                 if response is None:
@@ -212,20 +211,16 @@ class VCR(object):
                 )
             )
 
-        hosts_to_ignore = list(ignore_hosts)
+        hosts_to_ignore = set(ignore_hosts)
         if ignore_localhost:
-            hosts_to_ignore.extend(('localhost', '0.0.0.0', '127.0.0.1'))
-
+            hosts_to_ignore.update(('localhost', '0.0.0.0', '127.0.0.1'))
         if hosts_to_ignore:
-            hosts_to_ignore = set(hosts_to_ignore)
             filter_functions.append(self._build_ignore_hosts(hosts_to_ignore))
 
         if before_record_request:
             if not isinstance(before_record_request, collections.Iterable):
                 before_record_request = (before_record_request,)
-            for function in before_record_request:
-                filter_functions.append(function)
-
+            filter_functions.extend(before_record_request)
         def before_record_request(request):
             request = copy.copy(request)
             for function in filter_functions:
@@ -233,7 +228,6 @@ class VCR(object):
                     break
                 request = function(request)
             return request
-
         return before_record_request
 
     @staticmethod
diff --git a/vcr/errors.py b/vcr/errors.py
index 1b40f91..bdc9701 100644
--- a/vcr/errors.py
+++ b/vcr/errors.py
@@ -3,8 +3,5 @@ class CannotOverwriteExistingCassetteException(Exception):
 
 
 class UnhandledHTTPRequestError(KeyError):
-    '''
-    Raised when a cassette does not c
-    ontain the request we want
-    '''
+    """Raised when a cassette does not contain the request we want."""
     pass