No mistake

surely; without fail; as, it will happen at the appointed time, and no mistake.

See also: Mistake

Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in classic literature ?
"No mistake, I assure you," the young man insisted.
Yes, it's a magnificent Roman camp, and no mistake, with gates and ditch and mounds, all as complete as it was twenty years after the strong old rogues left it.
But make no mistake about it, I want to win again,' she added.
MAKE no mistake, Saturday was a game that Boro lost by making mistakes, rather than one The Hornets won.
Let there be no mistake: This is not about tax shelters, but about the fundamental nature of Appeals.
Ultimately, the court rejected the companies' claims stating, "If the existence of a fact is not known to the contracting parties, they cannot have a belief concerning that fact; therefore there can be no mistake." (15) In other words, the court reasoned that because the existence of the tailings hazard was not recognized by the parties they could not have formed a mutually mistaken belief concerning it and, therefore, no mistake was extant giving rise to a remedy.