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A new study suggests that wine drinkers are often getting more than they bargained for when it comes to the ABV of their wines: Over half of the bottles tested in an extensive review came back containing a higher percentage of alcohol than was listed on the label.

In a report published in the Journal of Wine Economics, researchers tested nearly 100,000 bottles of wine from around the world and found that nearly 60 percent of those bottles contained more alcohol than was listed on the label, with the average overstatement coming in at 0.42 percent ABV. According to the Telegraph, reds from Chile and Spain were the worst offenders. Whites from America and Chile were also some of the most likely to understate their ABV.

However, probably the study’s most shocking finding—or maybe its least shocking, if you know the wine industry—is some winemakers’ admission that they deliberately misstate this information. “Wineries may have incentives to deliberately distort the information because they perceive a market preference for a particular range of alcohol content for a given style of wine or for other reasons, such as tax avoidance,” researchers wrote. As the authors point out, not only do consumers check the ABV of their wines, but tax rates in the U.S. also jump once a wine crosses the 14 percent ABV threshold.

But as lead author Julian Alston of the University of California-Davis states, these choices by winemakers affect consumers as well. “A discrepancy of 0.4 percentage points might not seem large relative to an actual value of 13.6 percent alcohol by volume, but even errors of this magnitude could lead consumers to underestimate the amount of alcohol they have consumed in ways that could have some consequences for their health and driving safety,” he said.

And just when you thought getting more alcohol for free sounded like a fun idea.