Between a Wednesday evening and a Friday afternoon in April, MOLT, the tool Cockroach Labs ships for migrating databases to CockroachDB, gained the ability to migrate from IBM Db2 sources. Db2, one of the first commercially available relational databases, has a rich SQL dialect, a complex type system, and a native wire protocol. Supporting it in MOLT meant a new schema converter, a new Fetch path for pulling rows out and getting them into CockroachDB, a new Verify path for comparing them once they were loaded, a vendored ANTLR grammar, a Docker image for CI, and more than ten thousand lines of