Trump and Clinton went head-to-head Monday night in a heated session at Hofstra University. The Republican candidate appeared to be shouting at some points and stumbled over his words at others.
When asked by reporters after the event what he thought of moderator Lester Holt's performance, Trump said: "I felt he was fine."
But he then lamented having a "defective mic."
"My mic was defective within the room," Trump told reporters.
He added: "I wonder ... Was that on purpose? Was that on purpose?"
It's not the first time Trump has taken issues with his audio set-ups. He blamed a "bad earpiece" for his refusal to condemn former Ku Klux Klan leader David Duke and interrupted a January rally in Pensacola, Florida, to complain about his microphone.
"I don't like this mic," he told that crowd. "Whoever the hell brought this mic system, don't pay this son of a b**** ... Don't pay him."