Fans of Irn Bru have started stockpiling the soft drink ahead of a planned change in recipe.
Makers of the fizzy favourite are changing the formula of the product to cut the sugar content by almost half.
It is part of a sugar-reduction programme by AG Barr before the government levy on sugary drinks comes into effect in 2018.
But fans have launched the "Hands off our Irn Bru" petition, attracting more than 6,000 signatures.
Irn Bru drinkers are angry after the manufacturer revealed the new flavour would appear in stores in January.
They have been taking to social media to vent their dismay, with stories of people buying up to 250 cans mentioned but not substantiated.
The Cumbernauld-based firm announced last year that it would cut Irn Bru's sugar content from about 10g per 100ml to just below 5g.
This will reduce the calorie count per can from just under 140 to about 66.
AG Barr said the move was part of a "long-standing sugar reduction programme".
'Rather pay more'
Heading the "Hands off our Irn Bru" petition is joiner Ryan Allan from Ayr.
He has already made preparations to preserve his favourite drink and has a stockpile for "when he is hungover".
He told the BBC's Kaye Adams programme: "I've got 24 glass bottles in my loft that will do me for emergencies."
His anger was mostly at what will be replacing the sugar: "I know its not going to be the same product and I don't want to get used to it.
"I know sugar has its concerns but so do sweeteners and people are not as aware of that as they should be.
"I know the stuff is about to hit the shelves now and I'm going to ask people to try it out of curiosity but if you don't like it don't buy it, vote with your pound."
On his change.org petition, he stated: "The government's 'sugar tax' that would apply to the sales of sugary drinks is similar to the way cigarettes and alcohol are taxed.
"I would far rather pay more for a bottle than have an altered recipe version."
And he added: "I believe that a responsible adult should have the choice as to what poisons they want to put in their body."
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A spokesperson from A.G. Barr said: "From January 2018 Irn Bru will continue to be made using the same secret Irn Bru flavour essence, but with less sugar.
"The vast majority of our drinkers want less sugar in their Irn Bru so that's what we're now offering.
"We know that our loyal drinkers love Irn Bru for its unique great taste and we've worked hard to deliver this.
"We ran lots of taste tests that showed most people can't tell the difference - 9 out of 10 regular Irn Bru drinkers told us we had a good or excellent taste match.
"Most shoppers can expect to buy Irn Bru with reduced sugar from later this month. Give it a try when it comes out."