Social media users are warning EU referendum voters to bring their own pens to polling booths on Thursday over fears that pencil marks on ballots could be compromised.
While pencils are traditionally provided by electoral staff inside each booth, it is not a legal obligation to use them.
Ballots with an 'X' marked in pen or pencil will be accepted and counted.
Other Twitter users poked fun at the drive to 'bring your own pen' saying that claims that the vote could be rigged are "paranoid".
The Electoral Reform Society has also taken to social media to reassure voters.
The Electoral Commission told ITV News that voters are welcome to bring a pen and that counts are observed by statutory observers to ensure neutrality.
Campaigners from both sides are also invited to counts to observe proceedings.
By tradition, pencils are available in polling booths for voters to mark their ballot papers. If a voter wishes to bring their own pen and use that, it's fine.
What are the rules when voting?
If you prefer you can use a pen, even if it's your own.
While voters are asked to mark a cross in the box corresponding to their choice, a tick would theoretically suffice as long as it is for one choice and your intention is clear.
If you make a mistake on the ballot paper, you can ask for another one and avoid the risk of it being counted as a spoilt ballot paper.
Do not sign your ballot as if your name is identifiable, your vote will be void. Laws state that votes should be anonymous.
Also avoid writing anything else on the ballot paper - such as a message to the Prime Minister - as this would be considered a spoilt ballot paper.
Children are allowed into the polling station but cannot mark the ballot paper for adults.
No discussion on political preferences is allowed in the polling station.
Political clothing in relation to the vote, such as a t-shirt saying 'Vote Leave' or 'Vote Remain', is not allowed as it could be deemed as intimidating.