diff --git a/README.md b/README.md
index 468dd97f..146bcf84 100644
--- a/README.md
+++ b/README.md
@@ -372,6 +372,8 @@ In case you want to declare different labels and values:
 f.association :company, label_method: :company_name, value_method: :id, include_blank: false
 ```
 
+Please note that the association helper is currently only tested with Active Record. It currently does not work well with Mongoid and depending on the ORM you're using your mileage may vary.
+
 ### Buttons
 
 All web forms need buttons, right? **SimpleForm** wraps them in the DSL, acting like a proxy:
diff --git a/lib/simple_form/form_builder.rb b/lib/simple_form/form_builder.rb
index 408e3c08..c5ff4956 100644
--- a/lib/simple_form/form_builder.rb
+++ b/lib/simple_form/form_builder.rb
@@ -169,6 +169,8 @@ module SimpleForm
     #
     # From the options above, only :collection can also be supplied.
     #
+    # Please note that the association helper is currently only tested with Active Record. Depending on the ORM you are using your mileage may vary.
+    #
     def association(association, options={}, &block)
       options = options.dup