gistfile1.diff

diff --git a/lib/active_record/mass_assignment_security/associations.rb b/lib/active_record/mass_assignment_security/associations.rb
index ade4d3a..e6b23a9 100644
--- a/lib/active_record/mass_assignment_security/associations.rb
+++ b/lib/active_record/mass_assignment_security/associations.rb
@@ -84,6 +84,18 @@ module ActiveRecord
       end

       private :build_record
+
+      def build_through_record(record)
+        build_through_record_without_protection(record)
+      end
+
+      def build_through_record_without_protection(record)
+        ensure_mutable
+
+        through_record = through_association.build through_scope_attributes, without_protection: true
+        through_record.send("#{source_reflection.name}=", record)
+        through_record
+      end
     end