diff --git a/app/logical/concerns/array_attribute.rb b/app/logical/concerns/array_attribute.rb
new file mode 100644
index 000000000..128e4f288
--- /dev/null
+++ b/app/logical/concerns/array_attribute.rb
@@ -0,0 +1,36 @@
+module ArrayAttribute
+  extend ActiveSupport::Concern
+
+  class_methods do
+    # Defines `<attribute>_string`, `<attribute>_string=`, and `<attribute>=`
+    # methods for converting an array attribute to or from a string.
+    #
+    # The `<attribute>=` setter parses strings into an array using the
+    # `parse` regex. The resulting strings can be converted to another type
+    # with the `cast` option.
+    def array_attribute(name, parse: /[^[:space:]]+/, cast: :itself)
+      mod = Module.new do
+        define_method "#{name}_string" do
+          send(name).join(" ")
+        end
+
+        define_method "#{name}_string=" do |value|
+          raise ArgumentError, "#{name} must be a String" unless value.respond_to?(:to_str)
+          send("#{name}=", value)
+        end
+
+        define_method "#{name}=" do |value|
+          if value.respond_to?(:to_str)
+            super value.to_str.scan(parse).map(&cast)
+          elsif value.respond_to?(:to_a)
+            super value.to_a
+          else
+            raise ArgumentError, "#{name} must be a String or an Array"
+          end
+        end
+      end
+
+      prepend mod
+    end
+  end
+end
diff --git a/app/logical/concerns/normalizable.rb b/app/logical/concerns/normalizable.rb
index 7cad97e61..e3b1b54d2 100644
--- a/app/logical/concerns/normalizable.rb
+++ b/app/logical/concerns/normalizable.rb
@@ -3,10 +3,14 @@ module Normalizable
 
   class_methods do
     def normalize(attribute, method_name)
-      define_method("#{attribute}=") do |value|
-        normalized_value = self.class.send(method_name, value)
-        super(normalized_value)
+      mod = Module.new do
+        define_method("#{attribute}=") do |value|
+          normalized_value = self.class.send(method_name, value)
+          super(normalized_value)
+        end
       end
+
+      prepend mod
     end
 
     private
diff --git a/app/models/application_record.rb b/app/models/application_record.rb
index fc8391890..67fab07f0 100644
--- a/app/models/application_record.rb
+++ b/app/models/application_record.rb
@@ -4,6 +4,7 @@ class ApplicationRecord < ActiveRecord::Base
   include Deletable
   include Mentionable
   include Normalizable
+  include ArrayAttribute
   extend HasBitFlags
   extend Searchable
 
@@ -157,37 +158,6 @@ class ApplicationRecord < ActiveRecord::Base
     end
   end
 
-  concerning :AttributeMethods do
-    class_methods do
-      # Defines `<attribute>_string`, `<attribute>_string=`, and `<attribute>=`
-      # methods for converting an array attribute to or from a string.
-      #
-      # The `<attribute>=` setter parses strings into an array using the
-      # `parse` regex. The resulting strings can be converted to another type
-      # with the `cast` option.
-      def array_attribute(name, parse: /[^[:space:]]+/, cast: :itself)
-        define_method "#{name}_string" do
-          send(name).join(" ")
-        end
-
-        define_method "#{name}_string=" do |value|
-          raise ArgumentError, "#{name} must be a String" unless value.respond_to?(:to_str)
-          send("#{name}=", value)
-        end
-
-        define_method "#{name}=" do |value|
-          if value.respond_to?(:to_str)
-            super value.to_str.scan(parse).map(&cast)
-          elsif value.respond_to?(:to_a)
-            super value.to_a
-          else
-            raise ArgumentError, "#{name} must be a String or an Array"
-          end
-        end
-      end
-    end
-  end
-
   def warnings
     @warnings ||= ActiveModel::Errors.new(self)
   end
diff --git a/app/models/wiki_page.rb b/app/models/wiki_page.rb
index d9da10bd4..20531edac 100644
--- a/app/models/wiki_page.rb
+++ b/app/models/wiki_page.rb
@@ -10,12 +10,13 @@ class WikiPage < ApplicationRecord
   normalize :body, :normalize_text
   normalize :other_names, :normalize_other_names
 
+  array_attribute :other_names # XXX must come after `normalize :other_names`
+
   validates :title, tag_name: true, presence: true, uniqueness: true, if: :title_changed?
   validates :body, presence: true, unless: -> { is_deleted? || other_names.present? }
   validate :validate_rename
   validate :validate_other_names
 
-  array_attribute :other_names
   has_one :tag, :foreign_key => "name", :primary_key => "title"
   has_one :artist, -> { active }, foreign_key: "name", primary_key: "title"
   has_many :versions, -> {order("wiki_page_versions.id ASC")}, :class_name => "WikiPageVersion", :dependent => :destroy
diff --git a/test/unit/wiki_page_test.rb b/test/unit/wiki_page_test.rb
index 9b37af9f3..4b846115b 100644
--- a/test/unit/wiki_page_test.rb
+++ b/test/unit/wiki_page_test.rb
@@ -101,6 +101,10 @@ class WikiPageTest < ActiveSupport::TestCase
       should normalize_attribute(:other_names).from(["ＡＢＣ"]).to(["ABC"])
       should normalize_attribute(:other_names).from(["foo", "foo"]).to(["foo"])
       should normalize_attribute(:other_names).from(%w[foo*bar baz baz 加賀（艦これ）]).to(%w[foo*bar baz 加賀(艦これ)])
+
+      should normalize_attribute(:other_names).from("foo foo").to(["foo"])
+      should normalize_attribute(:other_names).from("foo bar").to(["foo", "bar"])
+      should normalize_attribute(:other_names).from("_foo_ Bar").to(["foo", "Bar"])
     end
 
     context "during title validation" do