Fix FPE on OS X

Change-Id: I50723807a269022c8e524fb06527a3c50fc045af
Reviewed-on: http://review.couchbase.org/44514
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>