The NSW Fire Commissioner has said Australia's most common smoke alarm should be banned.
Other experts have claimed the flawed alarms have failed to save thousands of lives.
In the last year more than 4000 NSW homes have caught alight.
Now experts are ringing alarm bells about our first line of defence - the smoke alarm.
"The ionisation alarm should immediately be banned," said Adrian Butler from the World Fire Safety Foundation.
There are two types of alarm: photoelectric and ionisation.
Put simply, photoelectric sees the smoke and ionisation smells it.
But it might not smell the smoke until it is too late.
"Ionisation alarms are prone to false alarms through cooking so people often disable them and take the battery out and photoelectric alarms generally react quicker in a household scenario," NSW Fire Brigades Commissioner Greg Mullins said.
Under parliamentary privilege, the Fire Commissioner went further, telling an inquiry: “My personal view is ionisation alarms should be banned."
"They do not operate as quickly as photoelectric alarms. Our own research re-enforces that," said Mr Mullins.
They look the same and cost about the same, but ionisation alarms can not detect smouldering fires and they are the ones experts want banned.
Most Australian homes - up to 90 per cent - have ionisation alarms.
In many fires, it is unlikely to start sounding until the smoke virtually chokes its sensors, which experts have said is a fatal flaw.
"Thousands of people have died over decades," said Mr Butler.
If you want to find out which alarm you have, all you need to do is take it off the roof and have a look at the back.
“If there's a radioactive symbol - it's an ionisation alarm. Take it away and replace it with a photoelectric," said fire commissioner, Mr Mullins.
The difference could be crucial.