diff --git a/activerecord/lib/active_record/validations/uniqueness.rb b/activerecord/lib/active_record/validations/uniqueness.rb
index 52e46e1ffe..cfa71a34d0 100644
--- a/activerecord/lib/active_record/validations/uniqueness.rb
+++ b/activerecord/lib/active_record/validations/uniqueness.rb
@@ -198,7 +198,7 @@ module ActiveRecord
       # can catch it and restart the transaction (e.g. by telling the user
       # that the title already exists, and asking him to re-enter the title).
       # This technique is also known as optimistic concurrency control:
-      # http://en.wikipedia.org/wiki/Optimistic_concurrency_control.
+      # http://en.wikipedia.org/wiki/Optimistic_concurrency_control .
       #
       # The bundled ActiveRecord::ConnectionAdapters distinguish unique index
       # constraint errors from other types of database errors by throwing an