1 files changed, 2 insertions, 2 deletions
diff --git a/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb b/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb
index 815e8eb97f..092b4ebd2f 100644
--- a/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb
+++ b/activerecord/lib/active_record/associations/builder/has_and_belongs_to_many.rb
@@ -98,7 +98,7 @@ module ActiveRecord::Associations::Builder
 
     def middle_options(join_model)
       middle_options = {}
-      middle_options[:class] = join_model
+      middle_options[:class_name] = "#{lhs_model.name}::#{join_model.name}"
       middle_options[:source] = join_model.left_reflection.name
       if options.key? :foreign_key
         middle_options[:foreign_key] = options[:foreign_key]
@@ -110,7 +110,7 @@ module ActiveRecord::Associations::Builder
       rhs_options = {}
 
       if options.key? :class_name
-        rhs_options[:foreign_key] = options[:class_name].foreign_key
+        rhs_options[:foreign_key] = options[:class_name].to_s.foreign_key
         rhs_options[:class_name] = options[:class_name]
       end