Make no mistake!
make no mistake
What I have said or am about to say is absolutely certain; do not think otherwise. Make no mistake, I intend to take this all the way to the Supreme Court if I have to. Make no mistake, this was a carefully orchestrated crime—not some amateur job.
Make no mistake (about it)!
Inf. Do not be mistaken! You can be certain. Sally: I'm very angry with you! Make no mistake about it! Fred: Whatever it's about, I'm sorry. Clerk: Make no mistake, this is the finest carpet available. Sally: I'd like something a little less fine, I think.