make sure of sth
phrasal verb.phrasal verb. To check something carefully so you can be certain that it is correct, true, or will happen.
phrasal verb. To take action to confirm or establish something with certainty; a transitive phrasal-prepositional verb.
I need to make sure of the time.
Before leaving, he double-checked the map to make sure of the route.
The detective meticulously reviewed the witness statements, determined to make sure of every last detail before presenting his case.
This form is often used with nouns like 'facts' or 'details'; the pattern 'make sure (that) + clause' is much more common.
Contrast with 'check' (the action of looking) and 'ensure' (more formal); 'make sure' is the action taken to become certain.
I want to make sure the facts.I want to make sure of the facts.When followed by a noun, the preposition 'of' is required; alternatively, use a 'that' clause.
Last updated April 24, 2026