Android Kotlin Gradle multiple .kts files

I'm trying to migrate from Groovy to Kotlin. My project has several .gradle files, like someFile.gradle, build.gradle, etc.

What I used to do in my app-level build.gradle: apply from: 'someFile.gradle'

My someFile.gradle:

apply plugin: 'com.some.plugin'

somePlugin {
    param1 'string'
    param2 'string'
    param3 false
}

My someFile.gradle.kts after migration:

import com.some.plugin.SomePluginExtension

apply(plugin = "com.some.plugin")

configure<SomePluginExtension> {
    param1 = "string"
    param2 = "string"
    param3 = false
}

My app-level build.gradle.kts after migration: apply(from = "someFile.gradle.kts")

When I try to sync the project with Gradle, I get this error on the line with import:

e: /p/a/t/h/project/someFile.gradle.kts:1:12: Unresolved reference: some

Other files, which have no imports work fine. How can I fix this error?