diff --git a/.rubocop.yml b/.rubocop.yml
index 64372a56..4fb9597f 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -1,3 +1,17 @@
+# The behavior of RuboCop can be controlled via the .rubocop.yml
+# configuration file. It makes it possible to enable/disable
+# certain cops (checks) and to alter their behavior if they accept
+# any parameters. The file can be placed either in your home
+# directory or in some project directory.
+#
+# RuboCop will start looking for the configuration file in the directory
+# where the inspected file is and continue its way up to the root directory.
+#
+# See https://docs.rubocop.org/rubocop/configuration
+
+inherit_mode:
+  merge:
+    - Exclude
 inherit_from: .rubocop_todo.yml
 
 AllCops:
diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index b213222f..6826af33 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -1,6 +1,6 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config --auto-gen-only-exclude --exclude-limit 100 --no-offense-counts --no-auto-gen-timestamp`
-# using RuboCop version 1.81.7.
+# using RuboCop version 1.84.2.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
@@ -18,12 +18,6 @@ Layout/TrailingWhitespace:
   Exclude:
     - 'spec/stack_master/commands/status_spec.rb'
 
-# This cop supports unsafe autocorrection (--autocorrect-all).
-# Configuration parameters: AllowSafeAssignment.
-Lint/AssignmentInCondition:
-  Exclude:
-    - 'lib/stack_master/parameter_resolvers/latest_container.rb'
-
 # Configuration parameters: AllowedMethods.
 # AllowedMethods: enums
 Lint/ConstantDefinitionInBlock:
@@ -41,11 +35,6 @@ Lint/DuplicateMethods:
     - 'lib/stack_master/stack_definition.rb'
     - 'lib/stack_master/test_driver/cloud_formation.rb'
 
-Lint/IneffectiveAccessModifier:
-  Exclude:
-    - 'lib/stack_master/parameter_loader.rb'
-    - 'lib/stack_master/template_compilers/sparkle_formation.rb'
-
 # This cop supports unsafe autocorrection (--autocorrect-all).
 # Configuration parameters: EnforcedStyle.
 # SupportedStyles: standard_error, runtime_error
@@ -99,11 +88,6 @@ Lint/SelfAssignment:
   Exclude:
     - 'lib/stack_master/cli.rb'
 
-# This cop supports safe autocorrection (--autocorrect).
-Lint/SendWithMixinArgument:
-  Exclude:
-    - 'lib/stack_master/sparkle_formation/template_file.rb'
-
 # Configuration parameters: AllowComments, AllowNil.
 Lint/SuppressedException:
   Exclude:
@@ -111,21 +95,12 @@ Lint/SuppressedException:
     - 'lib/stack_master/stack_events/streamer.rb'
     - 'lib/stack_master/stack_status.rb'
 
-# This cop supports safe autocorrection (--autocorrect).
-# Configuration parameters: IgnoreEmptyBlocks, AllowUnusedKeywordArguments.
-Lint/UnusedBlockArgument:
-  Exclude:
-    - 'features/step_definitions/parameter_store_steps.rb'
-    - 'lib/stack_master/stack_differ.rb'
-
 # This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: AllowUnusedKeywordArguments, IgnoreEmptyMethods, IgnoreNotImplementedMethods, NotImplementedExceptions.
 # NotImplementedExceptions: NotImplementedError
 Lint/UnusedMethodArgument:
   Exclude:
-    - 'lib/stack_master/test_driver/cloud_formation.rb'
     - 'lib/stack_master/test_driver/s3.rb'
-    - 'spec/stack_master/parameter_resolver_spec.rb'
     - 'spec/support/aws_stubs.rb'
 
 # This cop supports safe autocorrection (--autocorrect).
@@ -135,14 +110,6 @@ Lint/UselessAccessModifier:
     - 'lib/stack_master/parameter_loader.rb'
     - 'lib/stack_master/template_compilers/sparkle_formation.rb'
 
-# This cop supports safe autocorrection (--autocorrect).
-Lint/UselessAssignment:
-  Exclude:
-    - 'lib/stack_master/cli.rb'
-    - 'lib/stack_master/commands/tidy.rb'
-    - 'lib/stack_master/parameter_resolvers/latest_ami_by_tags.rb'
-    - 'lib/stack_master/template_compiler.rb'
-
 # This cop supports safe autocorrection (--autocorrect).
 # Configuration parameters: CheckForMethodsWithNoSideEffects.
 Lint/Void:
@@ -176,7 +143,6 @@ Metrics/AbcSize:
 # AllowedMethods: refine
 Metrics/BlockLength:
   Exclude:
-    - '**/*.gemspec'
     - 'example/simple/templates/myapp_vpc.rb'
     - 'spec/integration/drift_spec.rb'
     - 'spec/stack_master/aws_driver/s3_spec.rb'
@@ -320,7 +286,6 @@ Naming/AccessorMethodName:
 # AllowedAcronyms: CLI, DSL, ACL, API, ASCII, CPU, CSS, DNS, EOF, GUID, HTML, HTTP, HTTPS, ID, IP, JSON, LHS, QPS, RAM, RHS, RPC, SLA, SMTP, SQL, SSH, TCP, TLS, TTL, UDP, UI, UID, UUID, URI, URL, UTF8, VM, XML, XMPP, XSRF, XSS
 Naming/FileName:
   Exclude:
-    - 'Rakefile.rb'
     - 'spec/fixtures/templates/rb/cfndsl/sample-ctp-repeated.rb'
     - 'spec/fixtures/templates/rb/cfndsl/sample-ctp.rb'
 
@@ -352,7 +317,6 @@ Naming/MethodParameterName:
 # MethodDefinitionMacros: define_method, define_singleton_method
 Naming/PredicatePrefix:
   Exclude:
-    - 'spec/**/*'
     - 'lib/stack_master/parameter_resolvers/one_password.rb'
     - 'lib/stack_master/sparkle_formation/compile_time/definitions_validator.rb'
     - 'lib/stack_master/sparkle_formation/compile_time/empty_validator.rb'
@@ -405,8 +369,6 @@ Style/ClassAndModuleChildren:
 # Configuration parameters: AllowedConstants.
 Style/Documentation:
   Exclude:
-    - 'spec/**/*'
-    - 'test/**/*'
     - 'lib/stack_master.rb'
     - 'lib/stack_master/aws_driver/cloud_formation.rb'
     - 'lib/stack_master/aws_driver/s3.rb'
@@ -503,6 +465,13 @@ Style/GlobalStdStream:
     - 'lib/stack_master/cli.rb'
     - 'spec/stack_master/commands/apply_spec.rb'
 
+# This cop supports safe autocorrection (--autocorrect).
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: braces, no_braces
+Style/HashAsLastArrayItem:
+  Exclude:
+    - 'spec/integration/drift_spec.rb'
+
 # This cop supports unsafe autocorrection (--autocorrect-all).
 Style/HashTransformValues:
   Exclude:
@@ -541,7 +510,6 @@ Style/MutableConstant:
 # SupportedStyles: predicate, comparison
 Style/NumericPredicate:
   Exclude:
-    - 'spec/**/*'
     - 'lib/stack_master/cli.rb'
     - 'lib/stack_master/commands/events.rb'
     - 'lib/stack_master/commands/nag.rb'
diff --git a/CHANGELOG.md b/CHANGELOG.md
index b54ba730..3c799240 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,7 +10,12 @@ The format is based on [Keep a Changelog], and this project adheres to
 
 ## [Unreleased]
 
+### Fixed
+
+- Resolve lint issues identified by RuboCop. ([#401])
+
 [Unreleased]: https://github.com/envato/stack_master/compare/v2.18.0...HEAD
+[#401]: https://github.com/envato/stack_master/pull/401
 
 ## [2.18.0] - 2026-02-02
 
diff --git a/features/step_definitions/parameter_store_steps.rb b/features/step_definitions/parameter_store_steps.rb
index 384ca190..3fc425e1 100644
--- a/features/step_definitions/parameter_store_steps.rb
+++ b/features/step_definitions/parameter_store_steps.rb
@@ -1,5 +1,5 @@
 Given(/^(?:a|the)\ SSM\ parameter(?:\ named)?\ "([^"]*)"
-  \ with\ value\ "([^"]*)"\ in\ region\ "([^"]*)"$/x) do |parameter_name, parameter_value, parameter_region|
+  \ with\ value\ "([^"]*)"\ in\ region\ "([^"]*)"$/x) do |parameter_name, parameter_value, _parameter_region|
   Aws.config[:ssm] = {
     stub_responses: {
       get_parameter: {
diff --git a/lib/stack_master/cli.rb b/lib/stack_master/cli.rb
index b170c731..81389f9f 100644
--- a/lib/stack_master/cli.rb
+++ b/lib/stack_master/cli.rb
@@ -263,7 +263,7 @@ def default_config_file
     def load_config(file)
       stack_file = file || default_config_file
       StackMaster::Config.load!(stack_file)
-    rescue Errno::ENOENT => e
+    rescue Errno::ENOENT
       say "Failed to load config file #{stack_file}"
       @kernel.exit false
     end
@@ -301,7 +301,7 @@ def execute_stacks_command(command, args, options)
     end
 
     def show_other_region_candidates(config, stack_name)
-      candidates = config.filter(region = '', stack_name = stack_name)
+      candidates = config.filter('', stack_name = stack_name)
       return if candidates.empty?
 
       StackMaster.stdout.puts "Stack name #{stack_name} exists in regions: #{candidates.map(&:region).join(', ')}"
diff --git a/lib/stack_master/commands/tidy.rb b/lib/stack_master/commands/tidy.rb
index 49e3be51..0568ac72 100644
--- a/lib/stack_master/commands/tidy.rb
+++ b/lib/stack_master/commands/tidy.rb
@@ -5,13 +5,10 @@ class Tidy
       include StackMaster::Commands::TerminalHelper
 
       def perform
-        used_templates = []
-        used_parameter_files = []
-
         templates = Set.new(find_templates)
         parameter_files = Set.new(find_parameter_files)
 
-        status = @config.stacks.each do |stack_definition|
+        @config.stacks.each do |stack_definition|
           parameter_files.subtract(stack_definition.parameter_files_from_globs)
           template = File.absolute_path(stack_definition.template_file_path)
 
diff --git a/lib/stack_master/parameter_loader.rb b/lib/stack_master/parameter_loader.rb
index a9baf4e3..598f392b 100644
--- a/lib/stack_master/parameter_loader.rb
+++ b/lib/stack_master/parameter_loader.rb
@@ -1,46 +1,48 @@
 require 'active_support/core_ext/object/deep_dup'
 
 module StackMaster
-  class ParameterLoader
+  module ParameterLoader
     COMPILE_TIME_PARAMETERS_KEY = 'compile_time_parameters'
 
-    def self.load(parameter_files: [], parameters: {})
-      StackMaster.debug 'Searching for parameter files...'
-      all_parameters = parameter_files.map { |file_name| load_parameters(file_name) } + [parameters]
-      all_parameters.each_with_object({ template_parameters: {}, compile_time_parameters: {} }) do |parameters, hash|
-        template_parameters = create_template_parameters(parameters)
-        compile_time_parameters = create_compile_time_parameters(parameters)
-
-        merge_and_camelize(hash[:template_parameters], template_parameters)
-        merge_and_camelize(hash[:compile_time_parameters], compile_time_parameters)
+    class << self
+      def load(parameter_files: [], parameters: {})
+        StackMaster.debug 'Searching for parameter files...'
+        all_parameters = parameter_files.map { |file_name| load_parameters(file_name) } + [parameters]
+        all_parameters.each_with_object({ template_parameters: {}, compile_time_parameters: {} }) do |parameters, hash|
+          template_parameters = create_template_parameters(parameters)
+          compile_time_parameters = create_compile_time_parameters(parameters)
+
+          merge_and_camelize(hash[:template_parameters], template_parameters)
+          merge_and_camelize(hash[:compile_time_parameters], compile_time_parameters)
+        end
       end
-    end
 
-    private
+      private
 
-    def self.load_parameters(file_name)
-      file_exists = File.exist?(file_name)
-      StackMaster.debug file_exists ? "  #{file_name} found" : "  #{file_name} not found"
-      file_exists ? load_file(file_name) : {}
-    end
+      def load_parameters(file_name)
+        file_exists = File.exist?(file_name)
+        StackMaster.debug file_exists ? "  #{file_name} found" : "  #{file_name} not found"
+        file_exists ? load_file(file_name) : {}
+      end
 
-    def self.load_file(file_name)
-      YAML.load(File.read(file_name)) || {}
-    end
+      def load_file(file_name)
+        YAML.load(File.read(file_name)) || {}
+      end
 
-    def self.create_template_parameters(parameters)
-      parameters.deep_dup.tap do |parameters_clone|
-        parameters_clone.delete(COMPILE_TIME_PARAMETERS_KEY) ||
-          parameters_clone.delete(COMPILE_TIME_PARAMETERS_KEY.camelize)
+      def create_template_parameters(parameters)
+        parameters.deep_dup.tap do |parameters_clone|
+          parameters_clone.delete(COMPILE_TIME_PARAMETERS_KEY) ||
+            parameters_clone.delete(COMPILE_TIME_PARAMETERS_KEY.camelize)
+        end
       end
-    end
 
-    def self.create_compile_time_parameters(parameters)
-      (parameters[COMPILE_TIME_PARAMETERS_KEY] || parameters[COMPILE_TIME_PARAMETERS_KEY.camelize] || {}).deep_dup
-    end
+      def create_compile_time_parameters(parameters)
+        (parameters[COMPILE_TIME_PARAMETERS_KEY] || parameters[COMPILE_TIME_PARAMETERS_KEY.camelize] || {}).deep_dup
+      end
 
-    def self.merge_and_camelize(hash, parameters)
-      parameters.each { |key, value| hash[key.camelize] = value }
+      def merge_and_camelize(hash, parameters)
+        parameters.each { |key, value| hash[key.camelize] = value }
+      end
     end
   end
 end
diff --git a/lib/stack_master/parameter_resolvers/latest_ami_by_tags.rb b/lib/stack_master/parameter_resolvers/latest_ami_by_tags.rb
index af1416fd..2c5feb80 100644
--- a/lib/stack_master/parameter_resolvers/latest_ami_by_tags.rb
+++ b/lib/stack_master/parameter_resolvers/latest_ami_by_tags.rb
@@ -10,7 +10,7 @@ def initialize(config, stack_definition)
       end
 
       def resolve(value)
-        filters = @ami_finder.build_filters_from_string(value, prefix = 'tag')
+        filters = @ami_finder.build_filters_from_string(value, 'tag')
         @ami_finder.find_latest_ami(filters)&.image_id
       end
     end
diff --git a/lib/stack_master/parameter_resolvers/latest_container.rb b/lib/stack_master/parameter_resolvers/latest_container.rb
index a6d87edb..7dd01e2d 100644
--- a/lib/stack_master/parameter_resolvers/latest_container.rb
+++ b/lib/stack_master/parameter_resolvers/latest_container.rb
@@ -37,7 +37,7 @@ def resolve(parameters)
       def fetch_images(repository_name, registry_id, ecr)
         images = []
         next_token = nil
-        while resp = ecr.describe_images(
+        while (resp = ecr.describe_images(
           {
             repository_name: repository_name,
             registry_id: registry_id,
@@ -46,7 +46,7 @@ def fetch_images(repository_name, registry_id, ecr)
               tag_status: 'TAGGED'
             }
           }
-        )
+        ))
 
           images += resp.image_details
           next_token = resp.next_token
diff --git a/lib/stack_master/sparkle_formation/template_file.rb b/lib/stack_master/sparkle_formation/template_file.rb
index f6bb232c..78b3997a 100644
--- a/lib/stack_master/sparkle_formation/template_file.rb
+++ b/lib/stack_master/sparkle_formation/template_file.rb
@@ -61,5 +61,5 @@ def _user_data_file(file_name, vars = {})
   end
 end
 
-SparkleFormation::SparkleAttribute::Aws.send(:include, StackMaster::SparkleFormation::UserDataFile)
-SparkleFormation::SparkleAttribute::Aws.send(:include, StackMaster::SparkleFormation::JoinedFile)
+SparkleFormation::SparkleAttribute::Aws.include StackMaster::SparkleFormation::UserDataFile
+SparkleFormation::SparkleAttribute::Aws.include StackMaster::SparkleFormation::JoinedFile
diff --git a/lib/stack_master/stack_differ.rb b/lib/stack_master/stack_differ.rb
index a07a69fb..aeae7bd9 100644
--- a/lib/stack_master/stack_differ.rb
+++ b/lib/stack_master/stack_differ.rb
@@ -96,7 +96,7 @@ def output_diff
 
     def noecho_keys
       if @current_stack
-        @current_stack.parameters_with_defaults.select do |key, value|
+        @current_stack.parameters_with_defaults.select do |_key, value|
           value == '****'
         end.keys
       else
diff --git a/lib/stack_master/template_compiler.rb b/lib/stack_master/template_compiler.rb
index 6fcc5cc1..6394c78e 100644
--- a/lib/stack_master/template_compiler.rb
+++ b/lib/stack_master/template_compiler.rb
@@ -10,7 +10,7 @@ def self.compile(config, template_compiler, template_dir, template, compile_time
                  end
       compiler.require_dependencies
       compiler.compile(template_dir, template, compile_time_parameters, compiler_options)
-    rescue StandardError => e
+    rescue StandardError
       raise TemplateCompilationFailed, "Failed to compile #{template}"
     end
 
diff --git a/lib/stack_master/template_compilers/sparkle_formation.rb b/lib/stack_master/template_compilers/sparkle_formation.rb
index 40da8900..5b66f99f 100644
--- a/lib/stack_master/template_compilers/sparkle_formation.rb
+++ b/lib/stack_master/template_compilers/sparkle_formation.rb
@@ -3,80 +3,82 @@
 require 'stack_master/sparkle_formation/compile_time/state_builder'
 
 module StackMaster::TemplateCompilers
-  class SparkleFormation
+  module SparkleFormation
     CompileTime = StackMaster::SparkleFormation::CompileTime
 
-    def self.require_dependencies
-      require 'sparkle_formation'
-      require 'stack_master/sparkle_formation/template_file'
-    end
+    class << self
+      def require_dependencies
+        require 'sparkle_formation'
+        require 'stack_master/sparkle_formation/template_file'
+      end
 
-    def self.compile(template_dir, template, compile_time_parameters, compiler_options = {})
-      sparkle_template = compile_sparkle_template(template_dir, template, compiler_options)
-      definitions = sparkle_template.parameters
-      validate_definitions(definitions)
-      validate_parameters(definitions, compile_time_parameters)
+      def compile(template_dir, template, compile_time_parameters, compiler_options = {})
+        sparkle_template = compile_sparkle_template(template_dir, template, compiler_options)
+        definitions = sparkle_template.parameters
+        validate_definitions(definitions)
+        validate_parameters(definitions, compile_time_parameters)
 
-      sparkle_template.compile_time_parameter_setter do
-        sparkle_template.compile_state = create_state(definitions, compile_time_parameters)
+        sparkle_template.compile_time_parameter_setter do
+          sparkle_template.compile_state = create_state(definitions, compile_time_parameters)
+        end
+
+        JSON.pretty_generate(sparkle_template.dump)
       end
 
-      JSON.pretty_generate(sparkle_template.dump)
-    end
+      private
+
+      def compile_sparkle_template(template_dir, template, compiler_options)
+        sparkle_path =
+          if compiler_options['sparkle_path']
+            File.expand_path(compiler_options['sparkle_path'])
+          else
+            template_dir
+          end
+
+        collection = ::SparkleFormation::SparkleCollection.new
+        root_pack = ::SparkleFormation::Sparkle.new(
+          root: sparkle_path
+        )
+        collection.set_root(root_pack)
+        if compiler_options['sparkle_packs']
+          compiler_options['sparkle_packs'].each do |pack_name|
+            require pack_name
+            pack = ::SparkleFormation::SparklePack.new(name: pack_name)
+            collection.add_sparkle(pack)
+          end
+        end
 
-    private
+        if compiler_options['sparkle_pack_template']
+          unless collection.templates['aws'].include? template
+            raise ArgumentError.new("Template #{template.inspect} not found in any sparkle pack")
+          end
 
-    def self.compile_sparkle_template(template_dir, template, compiler_options)
-      sparkle_path =
-        if compiler_options['sparkle_path']
-          File.expand_path(compiler_options['sparkle_path'])
+          template_file_path = collection.templates['aws'][template].top['path']
         else
-          template_dir
+          template_file_path = File.join(template_dir, template)
         end
 
-      collection = ::SparkleFormation::SparkleCollection.new
-      root_pack = ::SparkleFormation::Sparkle.new(
-        root: sparkle_path
-      )
-      collection.set_root(root_pack)
-      if compiler_options['sparkle_packs']
-        compiler_options['sparkle_packs'].each do |pack_name|
-          require pack_name
-          pack = ::SparkleFormation::SparklePack.new(name: pack_name)
-          collection.add_sparkle(pack)
-        end
+        sparkle_template = compile_template_with_sparkle_path(template_file_path, sparkle_path)
+        sparkle_template.sparkle.apply(collection)
+        sparkle_template
       end
 
-      if compiler_options['sparkle_pack_template']
-        unless collection.templates['aws'].include? template
-          raise ArgumentError.new("Template #{template.inspect} not found in any sparkle pack")
-        end
-
-        template_file_path = collection.templates['aws'][template].top['path']
-      else
-        template_file_path = File.join(template_dir, template)
+      def compile_template_with_sparkle_path(template_path, sparkle_path)
+        ::SparkleFormation.sparkle_path = sparkle_path
+        ::SparkleFormation.compile(template_path, :sparkle)
       end
 
-      sparkle_template = compile_template_with_sparkle_path(template_file_path, sparkle_path)
-      sparkle_template.sparkle.apply(collection)
-      sparkle_template
-    end
-
-    def self.compile_template_with_sparkle_path(template_path, sparkle_path)
-      ::SparkleFormation.sparkle_path = sparkle_path
-      ::SparkleFormation.compile(template_path, :sparkle)
-    end
-
-    def self.validate_definitions(definitions)
-      CompileTime::DefinitionsValidator.new(definitions).validate
-    end
+      def validate_definitions(definitions)
+        CompileTime::DefinitionsValidator.new(definitions).validate
+      end
 
-    def self.validate_parameters(definitions, compile_time_parameters)
-      CompileTime::ParametersValidator.new(definitions, compile_time_parameters).validate
-    end
+      def validate_parameters(definitions, compile_time_parameters)
+        CompileTime::ParametersValidator.new(definitions, compile_time_parameters).validate
+      end
 
-    def self.create_state(definitions, compile_time_parameters)
-      CompileTime::StateBuilder.new(definitions, compile_time_parameters).build
+      def create_state(definitions, compile_time_parameters)
+        CompileTime::StateBuilder.new(definitions, compile_time_parameters).build
+      end
     end
 
     StackMaster::TemplateCompiler.register(:sparkle_formation, self)
diff --git a/lib/stack_master/test_driver/cloud_formation.rb b/lib/stack_master/test_driver/cloud_formation.rb
index baca3680..62f8797e 100644
--- a/lib/stack_master/test_driver/cloud_formation.rb
+++ b/lib/stack_master/test_driver/cloud_formation.rb
@@ -192,7 +192,7 @@ def delete_stack(options)
         @stacks.delete(stack_name)
       end
 
-      def validate_template(options)
+      def validate_template(_options)
         true
       end
 
diff --git a/spec/stack_master/parameter_resolver_spec.rb b/spec/stack_master/parameter_resolver_spec.rb
index fa9cc3e4..f63ebf6d 100644
--- a/spec/stack_master/parameter_resolver_spec.rb
+++ b/spec/stack_master/parameter_resolver_spec.rb
@@ -20,7 +20,7 @@ def resolve(value)
     Class.new do
       def initialize(config, region); end
 
-      def resolve(value)
+      def resolve(_value)
         raise Aws::CloudFormation::Errors::ValidationError.new(nil, "Can't find stack")
       end
     end