diff --git a/codegen-sbt/src/main/scala/caliban/codegen/CompileTimeCalibanPlugin.scala b/codegen-sbt/src/main/scala/caliban/codegen/CompileTimeCalibanPlugin.scala
index d06f421549..f9c629ea62 100644
--- a/codegen-sbt/src/main/scala/caliban/codegen/CompileTimeCalibanPlugin.scala
+++ b/codegen-sbt/src/main/scala/caliban/codegen/CompileTimeCalibanPlugin.scala
@@ -82,16 +82,16 @@ object CompileTimeCalibanServerPlugin extends AutoPlugin {
                        |
                        |import caliban.tools.compiletime.CompileTime
                        |import caliban.tools.compiletime.Config.ClientGenerationSettings
-                       |import zio.{ExitCode, URIO}
                        |
                        |private[generator] object $generatorName {
-                       |  def main(args: Array[String]): Unit =
-                       |    zio.Runtime.default.unsafeRun(
+                       |  def main(args: Array[String]): Unit = {
+                       |    val _  = zio.Runtime.default.unsafeRun(
                        |      CompileTime.generateClient(args.toList)(
                        |        $ref,
                        |        ${clientSettings.asScalaCode}
                        |      )
                        |    )
+                       |  }
                        |}
                        |""".stripMargin.trim
 
diff --git a/codegen-sbt/src/sbt-test/compiletime-codegen/test-compile/build.sbt b/codegen-sbt/src/sbt-test/compiletime-codegen/test-compile/build.sbt
index ed6205b677..fcc157541b 100644
--- a/codegen-sbt/src/sbt-test/compiletime-codegen/test-compile/build.sbt
+++ b/codegen-sbt/src/sbt-test/compiletime-codegen/test-compile/build.sbt
@@ -4,12 +4,13 @@ import sbt.librarymanagement.Resolver
 Global / onChangedBuildSource := ReloadOnSourceChanges
 
 ThisBuild / organization := "Conduktor"
-ThisBuild / homepage := Some(url("https://www.conduktor.io/"))
-ThisBuild / licenses := List("Apache-2.0" -> url("http://www.apache.org/licenses/LICENSE-2.0"))
-ThisBuild / version := "0.0.1"
+ThisBuild / homepage     := Some(url("https://www.conduktor.io/"))
+ThisBuild / licenses     := List("Apache-2.0" -> url("http://www.apache.org/licenses/LICENSE-2.0"))
+ThisBuild / version      := "0.0.1"
 ThisBuild / scalaVersion := "2.12.14" // Must stay 2.12 in these tests because the plugin is compiled with 2.12
 ThisBuild / resolvers += Resolver.mavenLocal
 ThisBuild / resolvers += Resolver.sonatypeRepo("snapshots")
+ThisBuild / scalacOptions ++= Seq("-Xfatal-warnings", "-feature")
 
 // ### Dependencies ###
 
@@ -54,7 +55,7 @@ lazy val root =
           preserveExecutable = args(2).toBoolean
         )
       },
-      InputKey[Unit]("sed-in-place") := {
+      InputKey[Unit]("sed-in-place")           := {
         val args: Vector[String] = spaceDelimited("<arg>").parsed.toVector
 
         val previousValue = args(0)
@@ -120,7 +121,7 @@ lazy val postsClients =
     .in(file("modules/posts-clients"))
     .enablePlugins(CompileTimeCalibanClientPlugin)
     .settings(
-      Compile / ctCalibanClient / ctCalibanClientsSettings := Seq(posts),
+      Compile / ctCalibanClient / ctCalibanClientsSettings      := Seq(posts),
       Compile / ctCalibanClient / ctCalibanClientsVersionedCode := false
     )
 
diff --git a/codegen-sbt/src/sbt-test/compiletime-codegen/test-compile/modules/posts/src/main/scala/poc/caliban/posts/GraphQLApi.scala b/codegen-sbt/src/sbt-test/compiletime-codegen/test-compile/modules/posts/src/main/scala/poc/caliban/posts/GraphQLApi.scala
index 5d60e0aaa9..a471689426 100644
--- a/codegen-sbt/src/sbt-test/compiletime-codegen/test-compile/modules/posts/src/main/scala/poc/caliban/posts/GraphQLApi.scala
+++ b/codegen-sbt/src/sbt-test/compiletime-codegen/test-compile/modules/posts/src/main/scala/poc/caliban/posts/GraphQLApi.scala
@@ -8,6 +8,8 @@ import zio._
 import zio.duration.durationInt
 import zio.stream.ZStream
 
+import scala.language.higherKinds
+
 object Operations {
 
   final case class CreatePostMutationParams(authorName: AuthorName, title: PostTitle, content: PostContent)
diff --git a/codegen-sbt/src/sbt-test/compiletime-codegen/test-compile/modules/potatoes/src/main/scala/poc/caliban/potatoes/PotatoesApi.scala b/codegen-sbt/src/sbt-test/compiletime-codegen/test-compile/modules/potatoes/src/main/scala/poc/caliban/potatoes/PotatoesApi.scala
index d456e69956..4b26dfa18b 100644
--- a/codegen-sbt/src/sbt-test/compiletime-codegen/test-compile/modules/potatoes/src/main/scala/poc/caliban/potatoes/PotatoesApi.scala
+++ b/codegen-sbt/src/sbt-test/compiletime-codegen/test-compile/modules/potatoes/src/main/scala/poc/caliban/potatoes/PotatoesApi.scala
@@ -8,6 +8,8 @@ import zio._
 import zio.duration.durationInt
 import zio.stream.ZStream
 
+import scala.language.higherKinds
+
 object Operations {
 
   final case class MakeNewSpeciesMutationParams(name: Potato.Name, color: Potato.Color)
diff --git a/codegen-sbt/src/sbt-test/compiletime-codegen/test-compile/test b/codegen-sbt/src/sbt-test/compiletime-codegen/test-compile/test
index 27c2896c50..e063c05659 100644
--- a/codegen-sbt/src/sbt-test/compiletime-codegen/test-compile/test
+++ b/codegen-sbt/src/sbt-test/compiletime-codegen/test-compile/test
@@ -1,3 +1,7 @@
+# 0. Reset/clean project
+
+> clean
+
 # 1. Test code generation
 # ## From the 'posts' "default" config
 $ absent modules/posts-clients/target/scala-2.12/src_managed/main/generated/Client.scala