diff --git a/lib/activerecord-be_readonly/model.rb b/lib/activerecord-be_readonly/model.rb
index a07e904..8843ddf 100644
--- a/lib/activerecord-be_readonly/model.rb
+++ b/lib/activerecord-be_readonly/model.rb
@@ -1,3 +1,5 @@
+require 'active_support'
+
 module BeReadonly
   module Model
     extend ActiveSupport::Concern
diff --git a/lib/activerecord-be_readonly/now.rb b/lib/activerecord-be_readonly/now.rb
index 6b49c80..f73f9fd 100644
--- a/lib/activerecord-be_readonly/now.rb
+++ b/lib/activerecord-be_readonly/now.rb
@@ -1,3 +1,5 @@
+require 'active_support'
+
 module BeReadonly
   module Now
     extend ActiveSupport::Concern