Passing JVM args to SBT

My SBT build is echoing:

[error] Note: Some input files use unchecked or unsafe operations.
[error] Note: Recompile with -Xlin开发者_C百科t:unchecked for details.

How can I pass the -Xlint:unchecked argument to the javac process invoked by SBT?

See http://code.google.com/p/simple-build-tool/wiki/BuildConfiguration#Compile_Options

override def compileOptions = super.compileOptions ++ 
  compileOptions("-Xlint:unchecked")