Postgres Citext?

15:12:01.856 [info] create table users
** (Postgrex.Error) ERROR 42704 (undefined_object) type "citext" does not exist
    (ecto_sql 3.9.2) lib/ecto/adapters/sql.ex:913: Ecto.Adapters.SQL.raise_sql_call_error/1
    (elixir 1.14.2) lib/enum.ex:1658: Enum."-map/2-lists^map/1-0-"/2
    (ecto_sql 3.9.2) lib/ecto/adapters/sql.ex:1005: Ecto.Adapters.SQL.execute_ddl/4
    (ecto_sql 3.9.2) lib/ecto/migration/runner.ex:326: Ecto.Migration.Runner.log_and_execute_ddl/3
    (ecto_sql 3.9.2) lib/ecto/migration/runner.ex:117: anonymous fn/6 in Ecto.Migration.Runner.flush/0
    (elixir 1.14.2) lib/enum.ex:2468: Enum."-reduce/3-lists^foldl/2-0-"/3
    (ecto_sql 3.9.2) lib/ecto/migration/runner.ex:116: Ecto.Migration.Runner.flush/0
    (ecto_sql 3.9.2) lib/ecto/migration/runner.ex:289: Ecto.Migration.Runner.perform_operation/3