Is FreeBSD's "sh" shell vulnerable to Shellshock?

I've got a server for personal use running FreeBSD 10, and it doesn't have Bash installed and never did. However, it comes with the its own POSIX-compliant shell "sh". Do I have to worry about the Shellshock bug on my server? I tried running this infamous shell script and **didn't** get the "vulnerable" echo, but I don't know if that ensures that I am safe: env x='() { :;}; echo vulnerable' sh -c 'echo hello'