Appending Year to InstallDir

I want to append the current calendar year to the InstallDir so that:

InstallDir "C:\My App"

becomes:

InstallDir "C:\My App 2012"

I tried using some of the date functions but since InstallDir is defined at the beginning of the .nsi file it throws an error (can only be used in a function).

Any ideas? I want this to show up in the setup wizard in the default install folder.

You can use !define /date and use the define with InstallDir OR you can set $instdir with StrCpy in .onInit at runtime