Blockchain technology has proven to be an plausible, perhaps miraculous, underpinning for the sale, transfer and tracking of large integers. Libraries need to become adept in blockchain technology to the extent that they want to license, track and lend large integers. In other words, not ever. "Blockchain" is being used today to convey a magical aura to technical and commercial schemes with little justification for using blockchain. In every proposal for use of blockchain in libraries (not involving traffic in large integers) that I've examined, there has been no good reason, other than marketing, to invoke blockchain. Blockchain makes problems harder, vastly more expensive to solve, and completely resistant to scaling, and frequently inimical to library values of privacy and equity. Ironically, there are a number of technologies that have underpinnings common to blockchain that are ripe for more extensive exploitation in libraries. Git, peer-to-peer, cryptographic hashes, and public key signatures should all be in our tool chests. Let's resolve to use the blockchain bubble to advance our understanding and use of these underpinning technologies and steer clear of the inevitable blockchain bust.