diff --git a/.clang-tidy b/.clang-tidy
index 561f735..c6b6631 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -1,5 +1,5 @@
 # -*- mode: conf; fill-column: 100; -*-
-# Written for clang-tidy 9.
+# Written for clang-tidy 11.
 
 ---
 Checks:         '*,
@@ -26,19 +26,20 @@ Checks:         '*,
                 -fuchsia-statically-constructed-objects,
                 -google-readability-todo,
                 -modernize-use-trailing-return-type,
-                -fuchsia-multiple-inheritance'
-CheckOptions:   - { key: readability-identifier-naming.ClassCase,             value: CamelCase  }
-                # Clashes with constant private member prefix. (const int _var;)
-                # - { key: readability-identifier-naming.ConstantCase,          value: lower_case }
-                - { key: readability-identifier-naming.EnumCase,              value: lower_case }
-                - { key: readability-identifier-naming.FunctionCase,          value: lower_case }
+                -fuchsia-multiple-inheritance,
+                -llvmlibc*'
+FormatStyle:    file            # Use .clang-format.
+CheckOptions:   # ↓ Clashes with static private member prefix. (static int _var;) ↓
+                - { key: readability-identifier-naming.VariableCase,          value: lower_case }
                 - { key: readability-identifier-naming.MemberCase,            value: lower_case }
-                - { key: readability-identifier-naming.ParameterCase,         value: lower_case }
                 - { key: readability-identifier-naming.PrivateMemberCase,     value: lower_case }
                 - { key: readability-identifier-naming.PrivateMemberPrefix,   value: _          }
-                - { key: readability-identifier-naming.ProtextedMemberCase,   value: lower_case }
+                - { key: readability-identifier-naming.ProtectedMemberCase,   value: lower_case }
                 - { key: readability-identifier-naming.ProtectedMemberPrefix, value: _          }
+
+                - { key: readability-identifier-naming.ClassCase,             value: CamelCase  }
                 - { key: readability-identifier-naming.StructCase,            value: lower_case }
-                # Clashes with static private member prefix. (static int _var;)
-                # - { key: readability-identifier-naming.VariableCase,          value: lower_case }
+                - { key: readability-identifier-naming.EnumCase,              value: lower_case }
+                - { key: readability-identifier-naming.FunctionCase,          value: lower_case }
+                - { key: readability-identifier-naming.ParameterCase,         value: lower_case }
 ...