diff --git a/synapse/rulecheck/domain_rule_checker.py b/synapse/rulecheck/domain_rule_checker.py
index 256cca2ed1..c9771e0b66 100644
--- a/synapse/rulecheck/domain_rule_checker.py
+++ b/synapse/rulecheck/domain_rule_checker.py
@@ -35,6 +35,8 @@ spam_checker:
 
 Don't forget to consider if you can invite users from your own domain.
 """
+
+
 class DomainRuleChecker(object):
 
     def __init__(self, config):
diff --git a/tests/rulecheck/test_domainrulecheck.py b/tests/rulecheck/test_domainrulecheck.py
index 141c8e4445..1c068a397b 100644
--- a/tests/rulecheck/test_domainrulecheck.py
+++ b/tests/rulecheck/test_domainrulecheck.py
@@ -24,73 +24,75 @@ class DomainRuleCheckerTestCase(unittest.TestCase):
 
     def test_allowed(self):
         config = {
-          "default": False,
-          "domain_mapping": {
-              "source_one": [ "target_one", "target_two" ],
-              "source_two": [ "target_two" ]
-          }
+            "default": False,
+            "domain_mapping": {
+                "source_one": ["target_one", "target_two"],
+                "source_two": ["target_two"]
+            }
         }
         check = DomainRuleChecker(config)
-        self.assertTrue(check.user_may_invite("test:source_one","test:target_one", "room"))
-        self.assertTrue(check.user_may_invite("test:source_one","test:target_two", "room"))
-        self.assertTrue(check.user_may_invite("test:source_two","test:target_two", "room"))
-
+        self.assertTrue(check.user_may_invite("test:source_one",
+                                              "test:target_one", "room"))
+        self.assertTrue(check.user_may_invite("test:source_one",
+                                              "test:target_two", "room"))
+        self.assertTrue(check.user_may_invite("test:source_two",
+                                              "test:target_two", "room"))
 
     def test_disallowed(self):
         config = {
             "default": True,
             "domain_mapping": {
-                "source_one": [ "target_one", "target_two" ],
-                "source_two": [ "target_two" ]
+                "source_one": ["target_one", "target_two"],
+                "source_two": ["target_two"]
             }
         }
         check = DomainRuleChecker(config)
-        self.assertFalse(check.user_may_invite("test:source_one","test:target_three", "room"))
-        self.assertFalse(check.user_may_invite("test:source_two","test:target_three", "room"))
-        self.assertFalse(check.user_may_invite("test:source_two","test:target_one", "room"))
-
+        self.assertFalse(check.user_may_invite("test:source_one",
+                                               "test:target_three", "room"))
+        self.assertFalse(check.user_may_invite("test:source_two",
+                                               "test:target_three", "room"))
+        self.assertFalse(check.user_may_invite("test:source_two",
+                                               "test:target_one", "room"))
 
     def test_default_allow(self):
         config = {
-          "default": True,
-          "domain_mapping": {
-              "source_one": [ "target_one", "target_two" ],
-              "source_two": [ "target_two" ]
-          }
+            "default": True,
+            "domain_mapping": {
+                "source_one": ["target_one", "target_two"],
+                "source_two": ["target_two"]
+            }
         }
         check = DomainRuleChecker(config)
-        self.assertTrue(check.user_may_invite("test:source_three","test:target_one", "room"))
+        self.assertTrue(check.user_may_invite("test:source_three",
+                                              "test:target_one", "room"))
 
     def test_default_deny(self):
         config = {
-          "default": False,
-          "domain_mapping": {
-             "source_one": [ "target_one", "target_two" ],
-             "source_two": [ "target_two" ]
-          }
+            "default": False,
+            "domain_mapping": {
+                "source_one": ["target_one", "target_two"],
+                "source_two": ["target_two"]
+            }
         }
         check = DomainRuleChecker(config)
-        self.assertFalse(check.user_may_invite("test:source_three","test:target_one", "room"))
-
+        self.assertFalse(check.user_may_invite("test:source_three",
+                                               "test:target_one", "room"))
 
     def test_config_parse(self):
         config = {
-          "default": False,
-          "domain_mapping": {
-              "source_one": [ "target_one", "target_two" ],
-              "source_two": [ "target_two" ]
-          }
+            "default": False,
+            "domain_mapping": {
+                "source_one": ["target_one", "target_two"],
+                "source_two": ["target_two"]
+            }
         }
         self.assertEquals(config, DomainRuleChecker.parse_config(config))
 
-
     def test_config_parse_failure(self):
         config = {
-          "domain_mapping": {
-              "source_one": [ "target_one", "target_two" ],
-              "source_two": [ "target_two" ]
-          }
+            "domain_mapping": {
+                "source_one": ["target_one", "target_two"],
+                "source_two": ["target_two"]
+            }
         }
         self.assertRaises(ConfigError, DomainRuleChecker.parse_config, config)
-
-