diff --git a/.pylintrc b/.pylintrc
index 39cbf052d..bd988944c 100644
--- a/.pylintrc
+++ b/.pylintrc
@@ -36,7 +36,11 @@ disable=no-self-use,
         too-many-return-statements,
         duplicate-code,
         wrong-import-position,
-        no-else-return
+        no-else-return,
+        # https://github.com/PyCQA/pylint/issues/1698
+        unsupported-membership-test,
+        unsupported-assignment-operation,
+        unsubscriptable-object
 
 [BASIC]
 function-rgx=[a-z_][a-z0-9_]{2,50}$
diff --git a/qutebrowser/config/configfiles.py b/qutebrowser/config/configfiles.py
index 6439f9688..e1a10848e 100644
--- a/qutebrowser/config/configfiles.py
+++ b/qutebrowser/config/configfiles.py
@@ -162,16 +162,22 @@ class YamlConfig(QObject):
                 "'global' object is not a dict")
             raise configexc.ConfigFileErrors('autoconfig.yml', [desc])
 
-        # Handle unknown/renamed keys
-        for name in list(global_obj):
+        self._values = global_obj
+        self._dirty = False
+
+        self._handle_migrations()
+
+    def _handle_migrations(self):
+        """Handle unknown/renamed keys."""
+        for name in list(self._values):
             if name in configdata.MIGRATIONS.renamed:
                 new_name = configdata.MIGRATIONS.renamed[name]
                 log.config.debug("Renaming {} to {}".format(name, new_name))
-                global_obj[new_name] = global_obj[name]
-                del global_obj[name]
+                self._values[new_name] = self._values[name]
+                del self._values[name]
             elif name in configdata.MIGRATIONS.deleted:
                 log.config.debug("Removing {}".format(name))
-                del global_obj[name]
+                del self._values[name]
             elif name in configdata.DATA:
                 pass
             else:
@@ -180,9 +186,6 @@ class YamlConfig(QObject):
                     "Unknown option {}".format(name))
                 raise configexc.ConfigFileErrors('autoconfig.yml', [desc])
 
-        self._values = global_obj
-        self._dirty = False
-
     def unset(self, name):
         """Remove the given option name if it's configured."""
         try:
diff --git a/tests/unit/config/test_configexc.py b/tests/unit/config/test_configexc.py
index 2eb44372e..03248731b 100644
--- a/tests/unit/config/test_configexc.py
+++ b/tests/unit/config/test_configexc.py
@@ -45,7 +45,7 @@ def test_no_option_error(deleted, renamed, expected):
 
 def test_no_option_error_clash():
     with pytest.raises(AssertionError):
-        e = configexc.NoOptionError('opt', deleted=True, renamed='foo')
+        configexc.NoOptionError('opt', deleted=True, renamed='foo')
 
 
 def test_backend_error():
diff --git a/tests/unit/config/test_configinit.py b/tests/unit/config/test_configinit.py
index 702e39110..cf77d415e 100644
--- a/tests/unit/config/test_configinit.py
+++ b/tests/unit/config/test_configinit.py
@@ -103,7 +103,7 @@ class TestEarlyInit:
         else:
             assert config.instance._values == {}
 
-    @pytest.mark.parametrize('load_autoconfig', [True, False])
+    @pytest.mark.parametrize('load_autoconfig', [True, False])  # noqa
     @pytest.mark.parametrize('config_py', [True, 'error', False])
     @pytest.mark.parametrize('invalid_yaml', ['42', 'unknown', 'wrong-type',
                                               False])