3 files changed, 11 insertions, 2 deletions
diff --git a/activemodel/lib/active_model/validations.rb b/activemodel/lib/active_model/validations.rb
index 708557f4ae..c69cabc888 100644
--- a/activemodel/lib/active_model/validations.rb
+++ b/activemodel/lib/active_model/validations.rb
@@ -133,6 +133,9 @@ module ActiveModel
         _validators[attribute.to_sym]
       end
 
+      def attribute_method?(attribute)
+        method_defined?(attribute)
+      end
     private
 
       def _merge_attributes(attr_names)
diff --git a/activemodel/lib/active_model/validations/acceptance.rb b/activemodel/lib/active_model/validations/acceptance.rb
index 0423fcd17f..fbd622eb6d 100644
--- a/activemodel/lib/active_model/validations/acceptance.rb
+++ b/activemodel/lib/active_model/validations/acceptance.rb
@@ -14,8 +14,10 @@ module ActiveModel
       def setup(klass)
         # Note: instance_methods.map(&:to_s) is important for 1.9 compatibility
         # as instance_methods returns symbols unlike 1.8 which returns strings.
-        new_attributes = attributes.reject { |name| klass.instance_methods.map(&:to_s).include?("#{name}=") }
-        klass.send(:attr_accessor, *new_attributes)        
+        attr_readers = attributes.reject { |name| klass.attribute_method?(name) }
+        attr_writers = attributes.reject { |name| klass.attribute_method?("#{name}=") }
+        klass.send(:attr_reader, *attr_readers)
+        klass.send(:attr_writer, *attr_writers)
       end
     end
 
diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 2d7cfad80d..8542c52d0c 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -931,6 +931,10 @@ module ActiveRecord #:nodoc:
         subclasses.each { |klass| klass.reset_inheritable_attributes; klass.reset_column_information }
       end
 
+      def attribute_method?(attribute)
+        super || column_names.include?(attribute.to_s.sub(/=$/, ''))
+      end
+
       # Set the lookup ancestors for ActiveModel.
       def lookup_ancestors #:nodoc:
         klass = self