diff --git a/activerecord/lib/active_record/session_store.rb b/activerecord/lib/active_record/session_store.rb
index 1c4ecda5b5..5db2905c95 100644
--- a/activerecord/lib/active_record/session_store.rb
+++ b/activerecord/lib/active_record/session_store.rb
@@ -182,7 +182,7 @@ module ActiveRecord
       ##
       # :singleton-method:
       # Use the ActiveRecord::Base.connection by default.
-      cattr_accessor :connection
+      cattr_writer :connection
 
       ##
       # :singleton-method: