CURRENT_TIMESTAMP and schema.rb syntax error

[atomical]

I have an updated_at field with a default value of CURRENT_TIMESTAMP.

When I use schema_validations and run rake db:migrate a syntax error appears in the schema.rb file

    t.datetime "updated_at",         :default=>#<Proc:0x00007f91da162ad8@(eval):1 (lambda)>

This happens only when I include schema_validations in the Gemfile. Rails 5.1.0.