diff --git a/gem/exe/repo b/gem/exe/repo
index 09d7ca96..451ca5d3 100755
--- a/gem/exe/repo
+++ b/gem/exe/repo
@@ -41,7 +41,7 @@ module RBICentral
           LOG
         end
 
-        if checks.none?
+        unless checks.any? # rubocop:disable Style/InvertibleUnlessCondition
           log("No change detected. Run with `--all` to run all checks.")
           return
         end
@@ -168,14 +168,16 @@ module RBICentral
     end
 
     class Main < Thor
-      extend T::Sig
-
       desc "check", "Check repo validity"
       subcommand "check", RBICentral::CLI::Check
 
-      sig { returns(T::Boolean) }
-      def self.exit_on_failure?
-        true
+      class << self
+        extend T::Sig
+
+        sig { returns(T::Boolean) }
+        def exit_on_failure?
+          true
+        end
       end
     end
   end
diff --git a/gem/lib/rbi-central.rb b/gem/lib/rbi-central.rb
index 453a19f3..1c3edf00 100644
--- a/gem/lib/rbi-central.rb
+++ b/gem/lib/rbi-central.rb
@@ -79,11 +79,15 @@ module RBICentral
 
   class Error < StandardError; end
 
-  sig { params(string: String).returns(String) }
-  def self.filter_parser_warning(string)
-    string
-      .gsub(/warning:.*\n/, "")
-      .gsub(/Please.*\n/, "")
+  class << self
+    extend T::Sig
+
+    sig { params(string: String).returns(String) }
+    def filter_parser_warning(string)
+      string
+        .gsub(/warning:.*\n/, "")
+        .gsub(/Please.*\n/, "")
+    end
   end
 end
 
diff --git a/gem/lib/rbi-central/cli/helper.rb b/gem/lib/rbi-central/cli/helper.rb
index f8a1b13b..603dec83 100644
--- a/gem/lib/rbi-central/cli/helper.rb
+++ b/gem/lib/rbi-central/cli/helper.rb
@@ -179,16 +179,20 @@ class ChecksSelection < T::Struct
         prop :runtime, T::Boolean
         prop :static, T::Boolean
 
-        sig { params(options: T::Hash[Symbol, T.untyped]).returns(ChecksSelection) }
-        def self.from_options(options)
-          ChecksSelection.new(
-            gem_tests: options[:gem],
-            index: options[:index],
-            rubocop: options[:rubocop],
-            rubygems: options[:rubygems],
-            runtime: options[:runtime],
-            static: options[:static],
-          )
+        class << self
+          extend T::Sig
+
+          sig { params(options: T::Hash[Symbol, T.untyped]).returns(ChecksSelection) }
+          def from_options(options)
+            ChecksSelection.new(
+              gem_tests: options[:gem],
+              index: options[:index],
+              rubocop: options[:rubocop],
+              rubygems: options[:rubygems],
+              runtime: options[:runtime],
+              static: options[:static],
+            )
+          end
         end
 
         sig { returns(T::Boolean) }
diff --git a/gem/lib/rbi-central/gem.rb b/gem/lib/rbi-central/gem.rb
index c9851697..d0ee97b3 100644
--- a/gem/lib/rbi-central/gem.rb
+++ b/gem/lib/rbi-central/gem.rb
@@ -13,15 +13,18 @@ class Error < RBICentral::Error; end
     const :dependencies, T::Array[String], default: []
     const :requires, T::Array[String], default: []
 
-    sig { params(name: String, object: T::Hash[String, T.untyped]).returns(Gem) }
-    def self.from_object(name, object = {})
-      Gem.new(
-        name: name,
-        path: object["path"],
-        source: object["source"],
-        dependencies: object["dependencies"] || [],
-        requires: object["requires"] || [],
-      )
+    class << self
+      extend T::Sig
+      sig { params(name: String, object: T::Hash[String, T.untyped]).returns(Gem) }
+      def from_object(name, object = {})
+        Gem.new(
+          name: name,
+          path: object["path"],
+          source: object["source"],
+          dependencies: object["dependencies"] || [],
+          requires: object["requires"] || [],
+        )
+      end
     end
 
     sig { params(_args: T.untyped).returns(T::Hash[String, T.untyped]) }
diff --git a/gem/lib/rbi-central/index.rb b/gem/lib/rbi-central/index.rb
index 9e57db9a..4acc1122 100644
--- a/gem/lib/rbi-central/index.rb
+++ b/gem/lib/rbi-central/index.rb
@@ -9,20 +9,24 @@ class Index < T::Struct
 
     class Error < RBICentral::Error; end
 
-    sig { params(object: T::Hash[String, T.untyped]).returns(Index) }
-    def self.from_object(object)
-      Index.new(gems: object.map { |name, gem_object| [name, Gem.from_object(name, gem_object)] }.to_h)
-    end
+    class << self
+      extend T::Sig
 
-    sig { params(before: Index, after: Index).returns(ChangeSet) }
-    def self.compare(before:, after:)
-      ChangeSet.new(
-        before: before,
-        after: after,
-        added: after.gems.values.select { |gem| !before.gem?(gem.name) },
-        removed: before.gems.values.select { |gem| !after.gem?(gem.name) },
-        updated: before.gems.values.select { |gem| after.gem?(gem.name) && after[gem.name] != gem },
-      )
+      sig { params(object: T::Hash[String, T.untyped]).returns(Index) }
+      def from_object(object)
+        Index.new(gems: object.map { |name, gem_object| [name, Gem.from_object(name, gem_object)] }.to_h)
+      end
+
+      sig { params(before: Index, after: Index).returns(ChangeSet) }
+      def compare(before:, after:)
+        ChangeSet.new(
+          before: before,
+          after: after,
+          added: after.gems.values.select { |gem| !before.gem?(gem.name) },
+          removed: before.gems.values.select { |gem| !after.gem?(gem.name) },
+          updated: before.gems.values.select { |gem| after.gem?(gem.name) && after[gem.name] != gem },
+        )
+      end
     end
 
     sig { params(name: String).returns(Gem) }
diff --git a/gem/test/rbi-central/repo_test.rb b/gem/test/rbi-central/repo_test.rb
index 748c744f..39bbb41d 100644
--- a/gem/test/rbi-central/repo_test.rb
+++ b/gem/test/rbi-central/repo_test.rb
@@ -61,7 +61,7 @@ def test_check_unexpected_annotations_files
 
       assert_messages(
         [
-          "Unexpected RBI annotations file `rbi/annotations/dir/file4.rbi` (must be in `rbi/annotations` root directory)",
+          "Unexpected RBI annotations file `rbi/annotations/dir/file4.rbi` (must be in `rbi/annotations` root directory)", # rubocop:disable Layout/LineLength
           "Unexpected RBI annotations file `rbi/annotations/file1` (should have `.rbi` extension)",
           "Unexpected RBI annotations file `rbi/annotations/file2.rb` (should have `.rbi` extension)",
           "Unexpected RBI annotations file `rbi/annotations/file3.RBI` (should have `.rbi` extension)",