diff --git a/build.mill b/build.mill
index 365a2225c13..9c2c741026a 100644
--- a/build.mill
+++ b/build.mill
@@ -411,7 +411,12 @@ trait MillScalaModule extends ScalaModule with MillJavaModule with ScalafixModul
       "-P:acyclic:force",
       "-feature",
       "-Xlint:unused",
-      "-Xlint:adapted-args"
+      "-Xlint:adapted-args",
+      "-Xsource:3",
+      "-Wconf:msg=inferred type changes:silent",
+      "-Wconf:msg=case companions no longer extend FunctionN:silent",
+      "-Wconf:msg=access modifiers for:silent",
+      "-Wconf:msg=found in a package prefix of the required type:silent"
     )
 
   def scalacPluginIvyDeps =
diff --git a/integration/feature/output-directory/src/OutputDirectoryLockTests.scala b/integration/feature/output-directory/src/OutputDirectoryLockTests.scala
index 13799e273aa..a8d6e6532ac 100644
--- a/integration/feature/output-directory/src/OutputDirectoryLockTests.scala
+++ b/integration/feature/output-directory/src/OutputDirectoryLockTests.scala
@@ -11,7 +11,7 @@ import scala.concurrent.{Await, ExecutionContext, Future}
 object OutputDirectoryLockTests extends UtestIntegrationTestSuite {
 
   private val pool = Executors.newCachedThreadPool()
-  private implicit val ec = ExecutionContext.fromExecutorService(pool)
+  private implicit val ec: ExecutionContext = ExecutionContext.fromExecutorService(pool)
 
   override def utestAfterAll(): Unit = {
     pool.shutdown()
diff --git a/main/eval/test/src/mill/eval/ModuleTests.scala b/main/eval/test/src/mill/eval/ModuleTests.scala
index 72750f5e081..f9160143c0c 100644
--- a/main/eval/test/src/mill/eval/ModuleTests.scala
+++ b/main/eval/test/src/mill/eval/ModuleTests.scala
@@ -9,7 +9,7 @@ import mill.define.Discover
 import utest._
 
 object TestExternalModule extends mill.define.ExternalModule with mill.define.TaskModule {
-  def defaultCommandName = "x"
+  def defaultCommandName() = "x"
   def x = Task { 13 }
   object inner extends mill.Module {
     def y = Task { 17 }
diff --git a/runner/src/mill/runner/MillBuildRootModule.scala b/runner/src/mill/runner/MillBuildRootModule.scala
index 10ae284a0af..7e1676849f0 100644
--- a/runner/src/mill/runner/MillBuildRootModule.scala
+++ b/runner/src/mill/runner/MillBuildRootModule.scala
@@ -226,7 +226,7 @@ abstract class MillBuildRootModule()(implicit
     )
   }
 
-  override def bindDependency: Task[Dep => BoundDep] = Task.Anon { dep: Dep =>
+  override def bindDependency: Task[Dep => BoundDep] = Task.Anon { (dep: Dep) =>
     super.bindDependency().apply(dep).exclude(resolveDepsExclusions(): _*)
   }
 
diff --git a/scalalib/src/mill/scalalib/CoursierModule.scala b/scalalib/src/mill/scalalib/CoursierModule.scala
index 4594916e4a0..a952acb62eb 100644
--- a/scalalib/src/mill/scalalib/CoursierModule.scala
+++ b/scalalib/src/mill/scalalib/CoursierModule.scala
@@ -23,7 +23,7 @@ trait CoursierModule extends mill.Module {
    * Bind a dependency ([[Dep]]) to the actual module contetxt (e.g. the scala version and the platform suffix)
    * @return The [[BoundDep]]
    */
-  def bindDependency: Task[Dep => BoundDep] = Task.Anon { dep: Dep =>
+  def bindDependency: Task[Dep => BoundDep] = Task.Anon { (dep: Dep) =>
     BoundDep((resolveCoursierDependency(): @nowarn).apply(dep), dep.force)
   }
 
@@ -80,7 +80,7 @@ trait CoursierModule extends mill.Module {
    * Map dependencies before resolving them.
    * Override this to customize the set of dependencies.
    */
-  def mapDependencies: Task[Dependency => Dependency] = Task.Anon { d: Dependency => d }
+  def mapDependencies: Task[Dependency => Dependency] = Task.Anon { (d: Dependency) => d }
 
   /**
    * The repositories used to resolved dependencies with [[resolveDeps()]].
diff --git a/scalalib/worker/src/mill/scalalib/worker/ZincWorkerImpl.scala b/scalalib/worker/src/mill/scalalib/worker/ZincWorkerImpl.scala
index 5b7c373992a..f8bb3ccdea5 100644
--- a/scalalib/worker/src/mill/scalalib/worker/ZincWorkerImpl.scala
+++ b/scalalib/worker/src/mill/scalalib/worker/ZincWorkerImpl.scala
@@ -144,7 +144,7 @@ class ZincWorkerImpl(
       compilerClasspath,
       scalacPluginClasspath,
       Seq()
-    ) { compilers: Compilers =>
+    ) { (compilers: Compilers) =>
       if (ZincWorkerUtil.isDotty(scalaVersion) || ZincWorkerUtil.isScala3Milestone(scalaVersion)) {
         // dotty 0.x and scala 3 milestones use the dotty-doc tool
         val dottydocClass =
@@ -388,7 +388,7 @@ class ZincWorkerImpl(
       compilerClasspath = compilerClasspath,
       scalacPluginClasspath = scalacPluginClasspath,
       javacOptions = javacOptions
-    ) { compilers: Compilers =>
+    ) { (compilers: Compilers) =>
       compileInternal(
         upstreamCompileOutput = upstreamCompileOutput,
         sources = sources,