Hahnemann spent a month on loan with Reading last season but returned to Fulham as the clubs couldn't agree a permanent deal.
When the 31-year-old's contract with the Cottagers expired in the Summer he chose to leave in an attempt to seek first team football elsewehere.
A deal with Reading was promptly completed, ensuring that Phil Whitehead had competition for the number one goalkeeper shirt.
Following Saturday's defeat at Leicester Whitehead was dropped giving Marcus a chance to impress and make the first-team berth his own.
Hahnemann kept a clean sheet against Burnley on Tuesday, despite not being tested much throughout the game he was delighted with his performance.
"I don't think that I really Had many saves to make in the first half, one cross was about it, but there were a couple of saves for me to make in the second half. Burnley put two up front later on and pinned us back a bit but Mackie and Williams did well," he said to readingfc.co.uk following the game.
"I've started my clean sheet run again so hopefully I can keep that going but we got three points and that's what really matters. If you get three points at this stage in the season you can really move up the table.
"When I came to Reading on loan last year I wanted to stay here but it didn't work out, now I'm back and I want to stay here a long time."