Chesterfield boss John Sheridan was relieved after his side managed to negotiate a difficult obstacle after beating Harrow 2-0.
After a valiant effort from the non-leaguers, Scott Boden broke the deadlock in the 74th minute before Craig Davies clinched victory in stoppage time.
"The FA Cup gives you these types of difficult games but we're in the next round which is the most important thing," said Sheridan.
"We're really happy with the way we played overall because I don't think they created too many problems for us.
"I wasn't happy with the way we played in the first-half because we lost the ball far too easily and against better teams we would have been punished and the lads have to learn from that."