diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index a9d256a771..7cddb9c601 100644
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -1354,8 +1354,7 @@ module ActiveRecord
         end
 
         def association_accessor_methods(reflection, association_proxy_class)
-          remove_possible_method(reflection.name)
-          define_method(reflection.name) do |*params|
+          redefine_method(reflection.name) do |*params|
             force_reload = params.first unless params.empty?
             association = association_instance_get(reflection.name)
 
@@ -1372,16 +1371,12 @@ module ActiveRecord
             association.target.nil? ? nil : association
           end
 
-          method = "loaded_#{reflection.name}?"
-          remove_possible_method(method)
-          define_method(method) do
+          redefine_method("loaded_#{reflection.name}?") do
             association = association_instance_get(reflection.name)
             association && association.loaded?
           end
-
-          method = "#{reflection.name}="
-          remove_possible_method(method)
-          define_method(method) do |new_value|
+          
+          redefine_method("#{reflection.name}=") do |new_value|
             association = association_instance_get(reflection.name)
 
             if association.nil? || association.target != new_value
@@ -1392,9 +1387,7 @@ module ActiveRecord
             association_instance_set(reflection.name, new_value.nil? ? nil : association)
           end
           
-          method = "set_#{reflection.name}_target"
-          remove_possible_method(method)
-          define_method(method) do |target|
+          redefine_method("set_#{reflection.name}_target") do |target|
             return if target.nil? and association_proxy_class == BelongsToAssociation
             association = association_proxy_class.new(self, reflection)
             association.target = target
@@ -1403,8 +1396,7 @@ module ActiveRecord
         end
 
         def collection_reader_method(reflection, association_proxy_class)
-          remove_possible_method(reflection.name)
-          define_method(reflection.name) do |*params|
+          redefine_method(reflection.name) do |*params|
             force_reload = params.first unless params.empty?
             association = association_instance_get(reflection.name)
 
@@ -1418,9 +1410,7 @@ module ActiveRecord
             association
           end
           
-          method = "#{reflection.name.to_s.singularize}_ids"
-          remove_possible_method(method)
-          define_method(method) do
+          redefine_method("#{reflection.name.to_s.singularize}_ids") do
             if send(reflection.name).loaded? || reflection.options[:finder_sql]
               send(reflection.name).map(&:id)
             else
@@ -1440,16 +1430,14 @@ module ActiveRecord
           collection_reader_method(reflection, association_proxy_class)
 
           if writer
-            define_method("#{reflection.name}=") do |new_value|
+            redefine_method("#{reflection.name}=") do |new_value|
               # Loads proxy class instance (defined in collection_reader_method) if not already loaded
               association = send(reflection.name)
               association.replace(new_value)
               association
             end
             
-            method = "#{reflection.name.to_s.singularize}_ids="
-            remove_possible_method(method)
-            define_method(method) do |new_value|
+            redefine_method("#{reflection.name.to_s.singularize}_ids=") do |new_value|
               ids = (new_value || []).reject { |nid| nid.blank? }.map(&:to_i)
               send("#{reflection.name}=", reflection.klass.find(ids).index_by(&:id).values_at(*ids))
             end
@@ -1457,9 +1445,7 @@ module ActiveRecord
         end
 
         def association_constructor_method(constructor, reflection, association_proxy_class)
-          method = "#{constructor}_#{reflection.name}"
-          remove_possible_method(method)
-          define_method(method) do |*params|
+          redefine_method("#{constructor}_#{reflection.name}") do |*params|
             attributees      = params.first unless params.empty?
             replace_existing = params[1].nil? ? true : params[1]
             association      = association_instance_get(reflection.name)
@@ -1500,9 +1486,8 @@ module ActiveRecord
         end
 
         def add_touch_callbacks(reflection, touch_attribute)
-          method_name = "belongs_to_touch_after_save_or_destroy_for_#{reflection.name}".to_sym
-          remove_possible_method(method_name)
-          define_method(method_name) do
+          method_name = :"belongs_to_touch_after_save_or_destroy_for_#{reflection.name}"
+          redefine_method(method_name) do
             association = send(reflection.name)
 
             if touch_attribute == true
diff --git a/activerecord/lib/active_record/fixtures.rb b/activerecord/lib/active_record/fixtures.rb
index 5bf43b3a72..657303fd14 100644
--- a/activerecord/lib/active_record/fixtures.rb
+++ b/activerecord/lib/active_record/fixtures.rb
@@ -871,7 +871,7 @@ module ActiveRecord
         table_names.each do |table_name|
           table_name = table_name.to_s.tr('./', '_')
 
-          define_method(table_name) do |*fixtures|
+          redefine_method(table_name) do |*fixtures|
             force_reload = fixtures.pop if fixtures.last == true || fixtures.last == :reload
 
             @fixture_cache[table_name] ||= {}
diff --git a/activerecord/lib/active_record/named_scope.rb b/activerecord/lib/active_record/named_scope.rb
index 849ec9c884..6596c695e2 100644
--- a/activerecord/lib/active_record/named_scope.rb
+++ b/activerecord/lib/active_record/named_scope.rb
@@ -105,7 +105,7 @@ module ActiveRecord
           extension ? relation.extending(extension) : relation
         end
 
-        singleton_class.send :define_method, name, &scopes[name]
+        singleton_class.send(:redefine_method, name, &scopes[name])
       end
 
       def named_scope(*args, &block)
diff --git a/activerecord/test/cases/adapters/mysql/active_schema_test.rb b/activerecord/test/cases/adapters/mysql/active_schema_test.rb
index 6e6645511c..ed4efdc1c0 100644
--- a/activerecord/test/cases/adapters/mysql/active_schema_test.rb
+++ b/activerecord/test/cases/adapters/mysql/active_schema_test.rb
@@ -101,6 +101,7 @@ class ActiveSchemaTest < ActiveRecord::TestCase
       #we need to actually modify some data, so we make execute point to the original method
       ActiveRecord::ConnectionAdapters::MysqlAdapter.class_eval do
         alias_method :execute_with_stub, :execute
+        remove_method :execute
         alias_method :execute, :execute_without_stub
       end
       yield