It is an unwelcome trait that has cost Pompey plenty of points this season.
And conceding late goals came back to haunt them once again at Exeter, as Ollie Watkins plundered a 90th-minute leveller.
That cancelled out Conor Chaplin’s first half opener and prevented the visitors from putting pressure on the top three.
And Paul Cook knows it is an ailment that his side must find a cure for soon if they are to enjoy success this term.
The Blues boss said: “We’re obviously very disappointed to concede yet another late goal.
“Exeter kept coming on to us and we couldn’t really do anything to stem that flow of attack after attack.
“I genuinely thought that they were good value for a point, but we’ve obviously got an issue with conceding around that time.
“There’s something in our side that allows that to happen – and it’s happened too often this season.
“You’d think that with the personnel we had on the pitch, we could do enough to see the match out.
“We must keep going and doing what we believe in, while also doing our best to correct that problem we’ve got.
“It’s vital that we find that important ingredient that is clearly missing from our side at the moment.”
Cook was also frustrated that Pompey were unable to build on Chaplin’s strike and put their opponents under more pressure.
He said: “We put ourselves in a great position, but we needed to score again and we didn’t really create any more clear-cut chances.
“It wasn’t a great game on a difficult pitch and we tried to be a bit more direct, but whatever we’re doing at the minute doesn’t seem to quite work.”
Watch Cook’s thoughts on the game below or subscribe to Pompey PlayerHD for extended interviews with the manager and Christian Burgess.