(CNN) They were billed as innovative, next-generation banknotes with added security -- but Australia's new $50 note also contain another feature: An unfortunate typo.
The $50 note (US$34.9) which entered general circulation last October has anti-counterfeiting measures including a swan that appears to fly and a holographic 50 that reverses when the note is moved.
Around 400 million new notes were printed -- and 46 million of them are in circulation, according to the central bank the Reserve Bank of Australia (RBA). The total value of the notes in circulation is around $2.3 billion (US$1.6 billion).
But an eagle-eyed observer has spotted a problem with the new notes: The word "Responsibility" is missing an "i."
Australia's Triple M radio station Thursday posted a close-up photo of the note on its Instagram account, showing the error.
The mistake -- which would be hard to spot with the naked eye -- is in microprint beside Edith Cowan, the first female member of an Australian parliament. The microprint next to her features excerpts from her maiden speech to the Western Australia state Parliament.
The RBA said it became aware of the issue last December, and the spelling would be corrected for the next print run around the middle of this year.
"These banknotes are legal tender and can continue to be used as normal. It does not affect their validity and functionality in any way," a spokeswoman said in a statement to CNN. "We have reviewed our processes to remove the likelihood of such an error occurring in the future."
David Unaipon, Australia's first published Aboriginal author, is also pictured on the notes alongside excerpts of Unaipon's book "Legendary Tales of the Australian Aborigines."
An RBA release last October described the $50 note as the "most popular note," accounting for nearly half of the total value of all those in circulation.
The RBA has already released new versions of the $5 and $10 banknotes, and an upgraded $20 note is expected later this year.