syntax error at or near boolean

I'm trying to make a boolean column NOT NULL, but for some reason this is failing. any ideas why?

ALTER TABLE public.pages
ALTER COLUMN branding boolean NOT NULL;

ALTER TABLE public.pages
ALTER COLUMN branding boolean NOT NULL;

ALTER TABLE public.pages
ALTER COLUMN branding boolean NOT NULL;

ALTER TABLE public.pages
ALTER COLUMN branding boolean NOT NULL;

Result:

syntax error at or near "boolean"

syntax error at or near "boolean"

syntax error at or near "boolean"

syntax error at or near "boolean"