diff --git a/activesupport/lib/active_support/core_ext/class/attribute.rb b/activesupport/lib/active_support/core_ext/class/attribute.rb
index 7928efb871..fa33ff945f 100644
--- a/activesupport/lib/active_support/core_ext/class/attribute.rb
+++ b/activesupport/lib/active_support/core_ext/class/attribute.rb
@@ -98,7 +98,7 @@ class Class
       singleton_class.silence_redefinition_of_method("#{name}?")
       define_singleton_method("#{name}?") { !!public_send(name) } if instance_predicate
 
-      ivar = "@#{name}"
+      ivar = "@#{name}".to_sym
 
       singleton_class.silence_redefinition_of_method("#{name}=")
       define_singleton_method("#{name}=") do |val|