diff --git a/.github/workflows/ruby.yml b/.github/workflows/ruby.yml
index d0e5e5c..8876e18 100644
--- a/.github/workflows/ruby.yml
+++ b/.github/workflows/ruby.yml
@@ -27,6 +27,12 @@ jobs:
         exclude:
           - rails-version: '5.2.8.1'
             ruby-version: '3.3'
+          - rails-version: 'main'
+            ruby-version: '2.7'
+          - rails-version: 'main'
+            ruby-version: '3.0'
+          - rails-version: 'main'
+            ruby-version: '3.1'
 
     env:
       RAILS_VERSION: ${{ matrix.rails-version }}
diff --git a/lib/route_downcaser/configuration.rb b/lib/route_downcaser/configuration.rb
index 2b1eef5..e056d4a 100644
--- a/lib/route_downcaser/configuration.rb
+++ b/lib/route_downcaser/configuration.rb
@@ -7,14 +7,14 @@ def configuration
     end
 
     def define_setting(name, default = nil)
-      class_variable_set("@@#{name}", default)
+      class_variable_set(:"@@#{name}", default)
 
       define_class_method "#{name}=" do |value|
-        class_variable_set("@@#{name}", value)
+        class_variable_set(:"@@#{name}", value)
       end
 
       define_class_method name do
-        class_variable_get("@@#{name}")
+        class_variable_get(:"@@#{name}")
       end
     end
 
diff --git a/lib/route_downcaser/downcase_route_middleware.rb b/lib/route_downcaser/downcase_route_middleware.rb
index f28daa7..7037128 100644
--- a/lib/route_downcaser/downcase_route_middleware.rb
+++ b/lib/route_downcaser/downcase_route_middleware.rb
@@ -20,7 +20,7 @@ def _call(env)
 
       # Downcase path_info if applicable
       path_info = downcased_uri(path_info)
-      path_info = path_info.gsub('%7E', '~') if path_info
+      path_info = path_info.gsub("%7E", "~") if path_info
 
       # If redirect configured, then return redirect request, if either
       # path_info has changed
diff --git a/lib/tasks/route_downcaser_tasks.rake b/lib/tasks/route_downcaser_tasks.rake
index 165cee6..b5144c0 100644
--- a/lib/tasks/route_downcaser_tasks.rake
+++ b/lib/tasks/route_downcaser_tasks.rake
@@ -1,4 +1,5 @@
 # frozen_string_literal: true
+
 # desc "Explaining what the task does"
 # task :route_downcaser do
 #   # Task goes here