diff --git a/plugin.py b/plugin.py
index 447f6e9..976c255 100644
--- a/plugin.py
+++ b/plugin.py
@@ -82,7 +82,8 @@ def on_workspace_configuration(self, params: Any, configuration: Dict) -> Dict:
                 self.resolve_working_directory(configuration, scope_uri, workspace_folder)
                 buf = session.get_session_buffer_for_uri_async(scope_uri)
                 if buf:
-                    configuration['validate'] = self.compute_validate(buf.language_id, scope_uri, configuration)
+                    configuration['validate'] = self.compute_validate(
+                        buf.get_language_id() or '', scope_uri, configuration)
                 else:
                     configuration['validate'] = 'on'
                 del configuration['probe']
diff --git a/tox.ini b/tox.ini
index 33fe5bd..3d9d8cb 100644
--- a/tox.ini
+++ b/tox.ini
@@ -11,9 +11,4 @@ skipsdist = True
 max-line-length = 120
 
 [flake8]
-ignore =
-    F841  # local variable is assigned to but never used
-    E252  # missing whitespace around parameter equals
-    W504  # line break after binary operator
-    F821  # undefined name
 max-line-length = 120