mysql: Illegal instruction: 4

I've just downloaded MAMP Stack 5.4.9 from the App Store. It installed and is running fine (i.e. I can access phpMyAdmin fine, created a database, etc).

I then went to command line to import my db extract (it was too large to import via phpMyAdmin). First I simply tried to access the database. At command line, I received:

Dennys-MacBook-Air:~/Library/Containers/com.bitnami.mampstack/Data/app/mysql/bin dswindle$ ./mysql -u root -p

Illegal instruction: 4

Any ideas what this means and how i might be able to access mysql from command-line?