A straightforward data point - the total supply of bitcoin hit 17 million.
But as with most things in crypto, it wasn't so simple.
Every 10 minutes or so, miners find a block of transactions and the network adds 12.5 new bitcoin to the total supply as a reward for the finders. And each reward has been logged on the blockchain since bitcoin launched in early 2009.
As such, it seemed like a number - a milestone - the industry could trust.
But as some celebrated once the mark was hit on bitcoin data provider Blockchain's website, others took to Twitter to rain on their parade.
Jameson Lopp, Casa engineer and the creator of Satoshi.info, another public-facing bitcoin data site, tweeted:
"Today I've learned that a lot of data sources are incorrectly reporting the total bitcoin supply. We haven't actually hit 17 million BTC yet."
Lopp's contention was that Blockchain.info, one of the most popular and highly-regarded sources for blockchain network data, among others, had not accounted for instances in which bitcoin miners, due to bugs and other causes, did not claim their full block reward.
More information: www.coindesk.com