1 files changed, 11 insertions, 0 deletions
diff --git a/activerecord/lib/active_record/associations/through_association.rb b/activerecord/lib/active_record/associations/through_association.rb
index f8a85b8a6f..9de9875b38 100644
--- a/activerecord/lib/active_record/associations/through_association.rb
+++ b/activerecord/lib/active_record/associations/through_association.rb
@@ -84,6 +84,17 @@ module ActiveRecord
             raise HasManyThroughNestedAssociationsAreReadonly.new(owner, reflection)
           end
         end
+
+        def build_record(attributes)
+          inverse = source_reflection.inverse_of
+          target = through_association.target
+
+          if inverse && target && !target.is_a?(Array)
+            attributes[inverse.foreign_key] = target.id
+          end
+
+          super(attributes)
+        end
     end
   end
 end