diff --git a/lib/replicate/active_record.rb b/lib/replicate/active_record.rb
index 6acdcee..2d78a1f 100644
--- a/lib/replicate/active_record.rb
+++ b/lib/replicate/active_record.rb
@@ -269,7 +269,11 @@ def replicate_find_existing_record(attributes)
         replicate_natural_key.each do |attribute_name|
           conditions[attribute_name] = attributes[attribute_name.to_s]
         end
-        find(:first, :conditions => conditions)
+        if ::ActiveRecord::VERSION::MAJOR >= 4
+          where(conditions).first
+        else
+          find(:first, :conditions => conditions)
+        end
       end
 
       # Update an AR object's attributes and persist to the database without
@@ -303,10 +307,10 @@ def replicate_disable_callbacks(instance)
           def instance.run_callbacks(*args); yield if block_given?; end
 
           # AR 3.0.x
-          def instance._run_save_callbacks(*args); yield; end
-          def instance._run_create_callbacks(*args); yield; end
-          def instance._run_update_callbacks(*args); yield; end
-          def instance._run_commit_callbacks(*args); yield; end
+          def instance._run_save_callbacks(*args); yield if block_given?; end
+          def instance._run_create_callbacks(*args); yield if block_given?; end
+          def instance._run_update_callbacks(*args); yield if block_given?; end
+          def instance._run_commit_callbacks(*args); yield if block_given?; end
         else
           # AR 2.x
           def instance.callback(*args)