Oldham ended non-league Kidderminster's hopes of a FA Cup first round upset with a comfortable win at Aggborough.
The League One side dominated early on, with Matt Derbyshire having an effort chalked off for offside.
However Harriers came close as Anthony Malbon headed at straight at keeper Dean Bouzanis from six yards.
And they were made to pay as Cristian Montano tucked home for the Latics, before Jose Baxter's clever free-kick rounded off proceedings.
VIEW FROM THE DRESSING ROOM
Oldham Athletic manager Paul Dickov told BBC Radio Manchester:
"Give Kidderminster credit because we knew it was going to be a tough game for us and they gave us that.
"The one thing that we said was really important was that we were really professional with and without the ball.
"The first goal settled everybody down and in the end, although they put a bit of pressure on us, I thought we were really resilient at the back.
"The main thing for us is that we're in the second round. That's all our focus has been on and we'll get who we're given in the draw."
Kidderminster manager Steve Burr told BBC Hereford & Worcester:
"I couldn't have asked for any more. They've given 100% and it was an exciting game for the neutral.
"Give credit to Oldham, they played very well for the first 20 minutes.
"In the second half, we threw everything at it but you need a bit of luck and we perhaps just didn't get those decisions that you need.
"Our fans were terrific and they've seen the lads have a go. Obviously we're disappointed to be out of the cup but we came up against a good side."