diff --git a/lib/rails3-jquery-autocomplete/orm/active_record.rb b/lib/rails3-jquery-autocomplete/orm/active_record.rb
index e9260dd0..db2fc07c 100644
--- a/lib/rails3-jquery-autocomplete/orm/active_record.rb
+++ b/lib/rails3-jquery-autocomplete/orm/active_record.rb
@@ -29,7 +29,7 @@ def get_autocomplete_items(parameters)
 
       def get_autocomplete_select_clause(model, method, options)
         table_name = model.table_name
-        (["#{table_name}.#{model.primary_key}", "#{table_name}.#{method}"] + (options[:extra_data].blank? ? [] : options[:extra_data]))
+        (["#{table_name}.#{model.primary_key || :id}", "#{table_name}.#{method}"] + (options[:extra_data].blank? ? [] : options[:extra_data]))
       end
 
       def get_autocomplete_where_clause(model, term, method, options)