Many ways to skin a concat. {# Broke #} {% set string = foo ~ ' ' ~ bar ~ '!' %} {# Woke #} {% set string = [foo, ' ', bar, '!']|join() %} {# Bespoke #} {% set string = "#{foo} #{bar}!" %} {# You do you, I guess… #} {% set string = "%s %s!"|format(foo, bar) %}