diff --git a/app/controllers/admin/stripe_connect_settings_controller.rb b/app/controllers/admin/stripe_connect_settings_controller.rb
index 54128e6bb0..11a5a2dc69 100644
--- a/app/controllers/admin/stripe_connect_settings_controller.rb
+++ b/app/controllers/admin/stripe_connect_settings_controller.rb
@@ -37,7 +37,7 @@ module Admin
 
     def obfuscated_secret_key
       key = Stripe.api_key
-      key.first(8) + "****" + key.last(4)
+      "#{key.first(8)}****#{key.last(4)}"
     end
 
     def settings_params
diff --git a/app/helpers/enterprises_helper.rb b/app/helpers/enterprises_helper.rb
index 4a7c6ae817..367b69b690 100644
--- a/app/helpers/enterprises_helper.rb
+++ b/app/helpers/enterprises_helper.rb
@@ -31,7 +31,7 @@ module EnterprisesHelper
 
   def enterprises_options(enterprises)
     enterprises.map { |enterprise|
-      [enterprise.name + ": " + enterprise.address.address1 + ", " + enterprise.address.city,
+      ["#{enterprise.name}: #{enterprise.address.address1}, #{enterprise.address.city}",
        enterprise.id.to_i]
     }
   end
diff --git a/app/helpers/spree/admin/base_helper.rb b/app/helpers/spree/admin/base_helper.rb
index 4d46a8e297..badeb0783d 100644
--- a/app/helpers/spree/admin/base_helper.rb
+++ b/app/helpers/spree/admin/base_helper.rb
@@ -108,7 +108,7 @@ module Spree
 
         object.preferences.keys.map { |key|
           preference_label = form.label("preferred_#{key}",
-                                        Spree.t(key.to_s.gsub("_from_list", "")) + ": ")
+                                        "#{Spree.t(key.to_s.gsub('_from_list', ''))}: ")
           preference_field = preference_field_for(
             form,
             "preferred_#{key}",
@@ -120,7 +120,7 @@ module Spree
 
       def link_to_add_fields(name, target, options = {})
         name = '' if options[:no_text]
-        css_classes = options[:class] ? options[:class] + " spree_add_fields" : "spree_add_fields"
+        css_classes = options[:class] ? "#{options[:class]} spree_add_fields" : "spree_add_fields"
         link_to_with_icon('icon-plus',
                           name,
                           'javascript:',
diff --git a/app/mailers/spree/user_mailer.rb b/app/mailers/spree/user_mailer.rb
index 02e24194bc..3797fcd9b4 100644
--- a/app/mailers/spree/user_mailer.rb
+++ b/app/mailers/spree/user_mailer.rb
@@ -25,7 +25,7 @@ module Spree
       @user = user
       I18n.with_locale valid_locale(@user) do
         mail(to: user.email,
-             subject: t(:welcome_to) + ' ' + Spree::Config[:site_name])
+             subject: "#{t(:welcome_to)} #{Spree::Config[:site_name]}")
       end
     end
 
diff --git a/app/models/enterprise.rb b/app/models/enterprise.rb
index 4af0fa374e..5a1ec12d23 100644
--- a/app/models/enterprise.rb
+++ b/app/models/enterprise.rb
@@ -376,7 +376,7 @@ class Enterprise < ApplicationRecord
   def category
     # Make this crazy logic human readable so we can argue about it sanely.
     cat = is_primary_producer ? "producer_" : "non_producer_"
-    cat << ("sells_" + sells)
+    cat << ("sells_#{sells}")
 
     # Map backend cases to front end cases.
     case cat
@@ -510,7 +510,7 @@ class Enterprise < ApplicationRecord
   end
 
   def correct_whatsapp_url(phone_number)
-    phone_number && ("https://wa.me/" + phone_number.tr('+ ', ''))
+    phone_number && "https://wa.me/#{phone_number.tr('+ ', '')}"
   end
 
   def correct_instagram_url(url)
diff --git a/app/models/spree/credit_card.rb b/app/models/spree/credit_card.rb
index 35a43ee828..74e40596a0 100644
--- a/app/models/spree/credit_card.rb
+++ b/app/models/spree/credit_card.rb
@@ -30,7 +30,7 @@ module Spree
 
     def expiry=(expiry)
       self[:month], self[:year] = expiry.split(" / ")
-      self[:year] = "20" + self[:year]
+      self[:year] = "20#{self[:year]}"
     end
 
     def number=(num)
diff --git a/app/models/spree/payment_method.rb b/app/models/spree/payment_method.rb
index a729571066..b66d8d239b 100644
--- a/app/models/spree/payment_method.rb
+++ b/app/models/spree/payment_method.rb
@@ -118,7 +118,7 @@ module Spree
     end
 
     def self.clean_name
-      i18n_key = "spree.admin.payment_methods.providers." + name.demodulize.downcase
+      i18n_key = "spree.admin.payment_methods.providers.#{name.demodulize.downcase}"
       I18n.t(i18n_key)
     end
 
diff --git a/app/serializers/api/cached_enterprise_serializer.rb b/app/serializers/api/cached_enterprise_serializer.rb
index bef58f0c77..d9e08a0155 100644
--- a/app/serializers/api/cached_enterprise_serializer.rb
+++ b/app/serializers/api/cached_enterprise_serializer.rb
@@ -131,7 +131,7 @@ module Api
         producer_shop: "map_003-producer-shop.svg",
         producer: "map_001-producer-only.svg",
       }
-      "/map_icons/" + (icons[enterprise.category] || "map_001-producer-only.svg")
+      "/map_icons/#{icons[enterprise.category] || 'map_001-producer-only.svg'}"
     end
 
     # Choose regular icon font for enterprises.
diff --git a/app/serializers/api/enterprise_shopfront_list_serializer.rb b/app/serializers/api/enterprise_shopfront_list_serializer.rb
index 8cd95c1547..6d99d3de57 100644
--- a/app/serializers/api/enterprise_shopfront_list_serializer.rb
+++ b/app/serializers/api/enterprise_shopfront_list_serializer.rb
@@ -21,7 +21,7 @@ module Api
         producer_shop: "map_003-producer-shop.svg",
         producer: "map_001-producer-only.svg",
       }
-      "/map_icons/" + (icons[enterprise.category] || "map_001-producer-only.svg")
+      "/map_icons/#{icons[enterprise.category] || 'map_001-producer-only.svg'}"
     end
 
     def icon_font
diff --git a/app/services/embedded_page_service.rb b/app/services/embedded_page_service.rb
index 1d4f344384..52fc4b98c4 100644
--- a/app/services/embedded_page_service.rb
+++ b/app/services/embedded_page_service.rb
@@ -59,7 +59,7 @@ class EmbeddedPageService
   def set_logout_redirect
     return unless enterprise_slug
 
-    @session[:shopfront_redirect] = '/' + enterprise_slug + '/shop?embedded_shopfront=true'
+    @session[:shopfront_redirect] = "/#{enterprise_slug}/shop?embedded_shopfront=true"
   end
 
   def enterprise_slug
diff --git a/lib/spree/api/controller_setup.rb b/lib/spree/api/controller_setup.rb
index 010ce77b1e..dcc49e15f9 100644
--- a/lib/spree/api/controller_setup.rb
+++ b/lib/spree/api/controller_setup.rb
@@ -22,7 +22,7 @@ module Spree
           include CanCan::ControllerAdditions
           include Spree::Core::ControllerHelpers::Auth
 
-          prepend_view_path Rails.root + "app/views"
+          prepend_view_path "#{Rails.root}app/views"
           append_view_path File.expand_path("../../../app/views", File.dirname(__FILE__))
         end
       end
diff --git a/lib/spree/core/environment_extension.rb b/lib/spree/core/environment_extension.rb
index 56d54517ea..78f8bf8c12 100644
--- a/lib/spree/core/environment_extension.rb
+++ b/lib/spree/core/environment_extension.rb
@@ -9,11 +9,11 @@ module Spree
         instance_variable_set "@#{name}", Set.new
 
         create_method( :"#{name}=" ) { |val|
-          instance_variable_set( "@" + name, val)
+          instance_variable_set( "@#{name}", val)
         }
 
         create_method(name.to_sym) do
-          instance_variable_get( "@" + name )
+          instance_variable_get( "@#{name}" )
         end
       end
 
diff --git a/spec/models/spree/line_item_spec.rb b/spec/models/spree/line_item_spec.rb
index ec596cec40..f68e2555d1 100644
--- a/spec/models/spree/line_item_spec.rb
+++ b/spec/models/spree/line_item_spec.rb
@@ -664,7 +664,7 @@ module Spree
         before { allow(li).to receive(:product) { p } }
 
         context "when full_name starts with the product name" do
-          before { allow(li).to receive(:full_name) { p.name + " - something" } }
+          before { allow(li).to receive(:full_name) { "#{p.name} - something" } }
 
           it "does not show the product name twice" do
             expect(li.product_and_full_name).to eq('product - something')
diff --git a/spec/models/spree/product_spec.rb b/spec/models/spree/product_spec.rb
index 993b1cb833..a19b853859 100644
--- a/spec/models/spree/product_spec.rb
+++ b/spec/models/spree/product_spec.rb
@@ -11,7 +11,7 @@ module Spree
       context '#duplicate' do
         it 'duplicates product' do
           clone = product.duplicate
-          expect(clone.name).to eq 'COPY OF ' + product.name
+          expect(clone.name).to eq "COPY OF #{product.name}"
           expect(clone.sku).to eq ""
           expect(clone.image).to eq product.image
         end
diff --git a/spec/services/embedded_page_service_spec.rb b/spec/services/embedded_page_service_spec.rb
index 6f201f625b..4ae9f91ba4 100644
--- a/spec/services/embedded_page_service_spec.rb
+++ b/spec/services/embedded_page_service_spec.rb
@@ -39,7 +39,7 @@ RSpec.describe EmbeddedPageService do
         expect(session[:embedded_shopfront]).to eq true
         expect(session[:embedding_domain]).to eq 'embedding-enterprise.com'
         expect(session[:shopfront_redirect])
-          .to eq '/' + enterprise_slug + '/shop?embedded_shopfront=true'
+          .to eq "/#{enterprise_slug}/shop?embedded_shopfront=true"
       end
 
       it "publicly reports that embedded layout should be used" do
@@ -58,7 +58,7 @@ RSpec.describe EmbeddedPageService do
         expect(session[:embedded_shopfront]).to eq true
         expect(session[:embedding_domain]).to eq 'embedding-enterprise.com'
         expect(session[:shopfront_redirect])
-          .to eq '/' + enterprise_slug + '/shop?embedded_shopfront=true'
+          .to eq "/#{enterprise_slug}/shop?embedded_shopfront=true"
       end
     end
 
diff --git a/spec/support/features/datepicker_helper.rb b/spec/support/features/datepicker_helper.rb
index 3840670f54..ffcfd8ef81 100644
--- a/spec/support/features/datepicker_helper.rb
+++ b/spec/support/features/datepicker_helper.rb
@@ -54,7 +54,7 @@ module Features
                    "select.flatpickr-monthDropdown-months").value.to_i + 1
       year = find(".flatpickr-calendar.open .flatpickr-current-month " \
                   ".numInputWrapper .cur-year").value
-      month.to_s + " " + year.to_s
+      "#{month} #{year}"
     end
 
     def pick_datetime(calendar_selector, datetime_selector)
diff --git a/spec/system/admin/products_spec.rb b/spec/system/admin/products_spec.rb
index e75f4bf3dd..9b2c4b7af5 100644
--- a/spec/system/admin/products_spec.rb
+++ b/spec/system/admin/products_spec.rb
@@ -690,7 +690,7 @@ RSpec.describe '
     end
 
     it "checks error when creating product image with unsupported format" do
-      unsupported_image_file_path = Rails.root + "README.md"
+      unsupported_image_file_path = "#{Rails.root}README.md"
       product = create(:simple_product, supplier: @supplier2)
 
       image = white_logo_file