The Jags keeper has recorded just one shut-out - in the SPFL Premiership opening night stalemate with Dundee United - so far this term.
Alan Archibald's side conceded another two strikes to Celtic on Sunday as their wait for a Firhill league win was extended once again.
Thistle have conceded 13 times in their 11 top-flight fixtures and Fox knows they must cut out the errors to put them on the road to victory.
The Firhill No.1 said: "I don't like losing goals. I am angry whenever we concede.
"It is something we need to address. We have been conceding more goals this year.
"It is not through a lack of effort or lack of hard work. We are just not doing the basics right at times.
"But we are playing at a higher level and against better quality teams, we knew it was going to be difficult for us to make the step up. We are being punished for our mistakes whereas last year we maybe weren't and we were getting breaks here and there.
"I am sure we will be fine, I am not too concerned. We are losing one or two a game and that is frustrating.
"But we are not being battered by teams in this league and losing heavily."
Despite a lack of clean sheets, Fox has been one of Thistle's most impressive performers in the opening weeks of the new campaign.
And the keeper is pleased with how Archibald's side have taken to the top flight.
He said: "We came so close on Sunday and when you put so much hard work into the game, it is gutting to get nothing.
"We rode the storm in the first half and after we got the goal to get back in it, we had a spell where we could have got the second one.
"They have got class and punished us for our mistakes. It is disappointing but we have to move on to the next game.
"Our away form has been really good so far so we are looking forward to going up to Pittodrie next week.
"We didn't do ourselves justice against Aberdeen at Firhill so hopefully we can pick ourselves up from Sunday and put that right on Monday night.
"We are sitting eighth in the table after the first quarter and we would have taken that at the start of the season. If you look at the performances, we could have had more points.
"Hopefully things even themselves out over the season and we have got a few wins coming our way because we know we could have won more games so far."