diff --git a/activerecord/lib/active_record/associations/builder/association.rb b/activerecord/lib/active_record/associations/builder/association.rb
index f45ab1aff4ece2616a96c545323b0aa2e341690a..c3f32b5ed9ed9a2c78451f0326ae1a82ac96b230 100644
--- a/activerecord/lib/active_record/associations/builder/association.rb
+++ b/activerecord/lib/active_record/associations/builder/association.rb
@@ -77,6 +77,16 @@ def define_writers
         end
       end
 
+      def check_valid_dependent!(dependent, valid_options)
+        unless valid_options.include?(dependent)
+          valid_options_message = valid_options.map(&:inspect).to_sentence(
+            words_connector: ', ', two_words_connector: ' or ', last_word_connector: ' or ')
+
+          raise ArgumentError, "The :dependent option expects either " \
+            "#{valid_options_message} (#{dependent.inspect})"
+        end
+      end
+
       def dependent_restrict_raises?
         ActiveRecord::Base.dependent_restrict_raises == true
       end
diff --git a/activerecord/lib/active_record/associations/builder/belongs_to.rb b/activerecord/lib/active_record/associations/builder/belongs_to.rb
index 4bef996297577fd1714271ca7c74ea4cd79d7a99..405dfc97b7cf2b7918deb3020d299c3fc1287dc2 100644
--- a/activerecord/lib/active_record/associations/builder/belongs_to.rb
+++ b/activerecord/lib/active_record/associations/builder/belongs_to.rb
@@ -72,16 +72,14 @@ def add_touch_callbacks(reflection)
       end
 
       def configure_dependency
-        if options[:dependent]
-          unless options[:dependent].in?([:destroy, :delete])
-            raise ArgumentError, "The :dependent option expects either :destroy or :delete (#{options[:dependent].inspect})"
-          end
+        if dependent = options[:dependent]
+          check_valid_dependent! dependent, [:destroy, :delete]
 
-          method_name = "belongs_to_dependent_#{options[:dependent]}_for_#{name}"
+          method_name = "belongs_to_dependent_#{dependent}_for_#{name}"
           model.send(:class_eval, <<-eoruby, __FILE__, __LINE__ + 1)
             def #{method_name}
               association = #{name}
-              association.#{options[:dependent]} if association
+              association.#{dependent} if association
             end
           eoruby
           model.after_destroy method_name
diff --git a/activerecord/lib/active_record/associations/builder/has_many.rb b/activerecord/lib/active_record/associations/builder/has_many.rb
index 81df1fb13561d8e00ddea4e90239000ef3f11c63..d0bdfa7d9ca3cb9c7d5c5534fadc2dd1cc886bc3 100644
--- a/activerecord/lib/active_record/associations/builder/has_many.rb
+++ b/activerecord/lib/active_record/associations/builder/has_many.rb
@@ -19,14 +19,11 @@ def build
     private
 
       def configure_dependency
-        if options[:dependent]
-          unless options[:dependent].in?([:destroy, :delete_all, :nullify, :restrict])
-            raise ArgumentError, "The :dependent option expects either :destroy, :delete_all, " \
-                                 ":nullify or :restrict (#{options[:dependent].inspect})"
-          end
+        if dependent = options[:dependent]
+          check_valid_dependent! dependent, [:destroy, :delete_all, :nullify, :restrict]
+          dependent_restrict_deprecation_warning if dependent == :restrict
 
-          dependent_restrict_deprecation_warning if options[:dependent] == :restrict
-          send("define_#{options[:dependent]}_dependency_method")
+          send("define_#{dependent}_dependency_method")
           model.before_destroy dependency_method_name
         end
       end
diff --git a/activerecord/lib/active_record/associations/builder/has_one.rb b/activerecord/lib/active_record/associations/builder/has_one.rb
index cdb45e8e58ffdd3fbde695ab6ec00b71cf0ed200..cd6d9c871b39e3f742e6e11abab5830bd5e0816d 100644
--- a/activerecord/lib/active_record/associations/builder/has_one.rb
+++ b/activerecord/lib/active_record/associations/builder/has_one.rb
@@ -25,14 +25,11 @@ def build
     private
 
       def configure_dependency
-        if options[:dependent]
-          unless options[:dependent].in?([:destroy, :delete, :nullify, :restrict])
-            raise ArgumentError, "The :dependent option expects either :destroy, :delete, " \
-                                 ":nullify or :restrict (#{options[:dependent].inspect})"
-          end
-
-          dependent_restrict_deprecation_warning if options[:dependent] == :restrict
-          send("define_#{options[:dependent]}_dependency_method")
+        if dependent = options[:dependent]
+          check_valid_dependent! dependent, [:destroy, :delete, :nullify, :restrict]
+          dependent_restrict_deprecation_warning if dependent == :restrict
+
+          send("define_#{dependent}_dependency_method")
           model.before_destroy dependency_method_name
         end
       end