I've been saying this for a while: Calvinism and Molinism are compatible.
Calvinism and Molinism: Bill Craig beat me to it | Right Reason
The thing is, though, many Molinists (including the best-known advocates) are Arminian, so when Calvinists (ostensibly) object to Molinism, they are often actually objecting to the underlying Arminian theology held by many (most?) Molinists. This is not to say that many Calvinists do not have actual objections to Molinism (the grounding problem, for one), just that these objections are distinct from the Calvinism/Arminianism debate. In fact, many of the most common objections to Molinism are put forth by Calvinists and Arminians.
HT: Steve Hays