make certain of

make certain of (something)

To check something in order to confirm that it is true, correct, or is happening. I just want call the restaurant and make certain of our reservations for tonight. I always get to the airport two hours early to be certain of making my flight.
See also: certain, make, of
Farlex Dictionary of Idioms.

make certain of something

to check something in order to be sure. Please make certain of what you want to do. Would you please make certain of the number of things you want to order?
See also: certain, make, of
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

make certain of something/of doing something

do something in order to be sure that something else will happen: You’ll have to leave soon to make certain of getting there on time.
See also: certain, make, of, something
Farlex Partner Idioms Dictionary
See also:
  • make certain of (something)
  • make certain of something/of doing something
  • take (something) as (the) gospel truth
  • take (something) as gospel
  • take (something) for (the) gospel truth
  • take (something) for gospel
  • take as gospel
  • take something as gospel
  • take something as/for gospel/gospel truth
  • leave the door open for (something or doing something)
References in periodicals archive
Both to ensure and to insure also mean to make certain of something.