How can I use the incubating Vector API from Kotlin in a Gradle build?

I want to use the new Vector API from a Kotlin project using a Gradle build.

I tried this:

tasks.withType<KotlinCompile> {
    kotlinOptions.jvmTarget = "17"
    kotlinOptions.freeCompilerArgs = listOf("--add-modules", "jdk.incubator.vector")
}

Result is:

Invalid argument: --add-modules

I've checked and the right SDK is being used, and help for javac at least shows --add-modules as a valid flag, so what I guess is going on is, this is the Kotlin compiler, and I need to provide a different flag, or some kind of prefixed flag to add a module to the classpath. What is the magic incantation here?