diff --git a/lib/active_admin/view_helpers/filter_form_helper.rb b/lib/active_admin/view_helpers/filter_form_helper.rb
index <HASH>..<HASH> 100644
--- a/lib/active_admin/view_helpers/filter_form_helper.rb
+++ b/lib/active_admin/view_helpers/filter_form_helper.rb
@@ -155,7 +155,7 @@ module ActiveAdmin
       end
 
       if reflection = reflection_for(method)
-        return :select if reflection.macro == :belongs_to && reflection.collection?
+        return :select if reflection.macro == :belongs_to && !reflection.options[:polymorphic]
       end
     end
Fix for specs. Filter forms shouldn't display polymorphic belongs_to