Saturday's 2-1 victory over Brighton was the second successive game Rovers have not conceded from open play, although they have given away a spot-kick in both those matches.
Parry has put his side's improvement at the back down to the whole team's performance and has urged Tranmere to continue that if they are to push up the League One table.
He said: "One of the reasons we are defending well is because of the strikers. When we took over the first aim was to address the defensive problem.
"One of the ways we have done that is we expect our front three to start defending at the front. They've done that brilliantly. The three of them work their socks off.
"That takes away a bit of their attacking potential and we accept that. We know what we're expecting of them and we're quite happy with their performances."