diff --git a/lib/pg_search.rb b/lib/pg_search.rb
index 594699a7..45bb85d2 100644
--- a/lib/pg_search.rb
+++ b/lib/pg_search.rb
@@ -108,5 +108,8 @@ def message
   end
 end
 
-require "pg_search/document"
+ActiveSupport.on_load(:active_record) do
+  require "pg_search/document"
+end
+
 require "pg_search/railtie" if defined?(Rails)