diff --git a/app/current/src/main/scala/io/scalajs/nodejs/fs/FSWatcher.scala b/app/current/src/main/scala/io/scalajs/nodejs/fs/FSWatcher.scala
index cac2e2e82..95825092f 100644
--- a/app/current/src/main/scala/io/scalajs/nodejs/fs/FSWatcher.scala
+++ b/app/current/src/main/scala/io/scalajs/nodejs/fs/FSWatcher.scala
@@ -28,7 +28,7 @@ object FSWatcher {
   /**
     * File System Watcher Extensions
     */
-  implicit class FSWatcherExtensions(val watcher: FSWatcher) extends AnyVal {
+  implicit final class FSWatcherExtensions(val watcher: FSWatcher) extends AnyVal {
 
     /**
       * Emitted when something changes in a watched directory or file. See more details in fs.watch().
diff --git a/app/current/src/main/scala/io/scalajs/nodejs/fs/ReadStream.scala b/app/current/src/main/scala/io/scalajs/nodejs/fs/ReadStream.scala
index 1ccfb0001..09b2037bc 100644
--- a/app/current/src/main/scala/io/scalajs/nodejs/fs/ReadStream.scala
+++ b/app/current/src/main/scala/io/scalajs/nodejs/fs/ReadStream.scala
@@ -57,7 +57,7 @@ object ReadStream {
   /**
     * Read Stream Events
     */
-  implicit class ReadStreamEvents(val stream: ReadStream) extends AnyVal {
+  implicit final class ReadStreamEvents(val stream: ReadStream) extends AnyVal {
 
     /**
       * Emitted when the ReadStream's underlying file descriptor has been closed using the fs.close() method.
@@ -83,7 +83,7 @@ object ReadStream {
   /**
     * Read Stream Extensions
     */
-  implicit class ReadStreamExtensions(val stream: ReadStream) extends AnyVal {
+  implicit final class ReadStreamExtensions(val stream: ReadStream) extends AnyVal {
 
     @inline
     def closeFuture: Future[Unit] = promiseCallback1[Unit](stream.close)
diff --git a/app/current/src/main/scala/io/scalajs/nodejs/fs/WriteStream.scala b/app/current/src/main/scala/io/scalajs/nodejs/fs/WriteStream.scala
index 730d5ff0d..1f079ae17 100644
--- a/app/current/src/main/scala/io/scalajs/nodejs/fs/WriteStream.scala
+++ b/app/current/src/main/scala/io/scalajs/nodejs/fs/WriteStream.scala
@@ -54,7 +54,7 @@ object WriteStream {
   /**
     * Write Stream Events
     */
-  implicit class WriteStreamEvents(val stream: WriteStream) extends AnyVal {
+  implicit final class WriteStreamEvents(val stream: WriteStream) extends AnyVal {
 
     /**
       * Emitted when the WriteStream's underlying file descriptor has been closed using the fs.close() method.
@@ -80,7 +80,7 @@ object WriteStream {
   /**
     * Write Stream Extensions
     */
-  implicit class WriteStreamExtensions(val stream: WriteStream) extends AnyVal {
+  implicit final class WriteStreamExtensions(val stream: WriteStream) extends AnyVal {
 
     @inline
     def closeFuture: Future[Unit] = promiseCallback1[Unit](stream.close)
diff --git a/app/current/src/main/scala/io/scalajs/nodejs/fs/package.scala b/app/current/src/main/scala/io/scalajs/nodejs/fs/package.scala
index 7d7a1d02f..c5a6d8320 100644
--- a/app/current/src/main/scala/io/scalajs/nodejs/fs/package.scala
+++ b/app/current/src/main/scala/io/scalajs/nodejs/fs/package.scala
@@ -36,7 +36,7 @@ package object fs {
     * File System Extensions
     * @param fs the given [[Fs file system]] instance
     */
-  final implicit class FsExtensions(private val fs: Fs) extends AnyVal {
+  implicit final class FsExtensions(private val fs: Fs) extends AnyVal {
     @inline
     def accessFuture(path: Buffer | String): Future[Unit] = {
       promiseWithError0[FileIOError](fs.access(path, _))
diff --git a/app/current/src/main/scala/io/scalajs/nodejs/http/Server.scala b/app/current/src/main/scala/io/scalajs/nodejs/http/Server.scala
index 88eef1048..9dd9baa50 100644
--- a/app/current/src/main/scala/io/scalajs/nodejs/http/Server.scala
+++ b/app/current/src/main/scala/io/scalajs/nodejs/http/Server.scala
@@ -32,7 +32,7 @@ object Server {
     * Server Events
     * @param server the given [[Server]]
     */
-  final implicit class ServerEvents(val server: Server) extends AnyVal {
+  implicit final class ServerEvents(val server: Server) extends AnyVal {
 
     /**
       * Emitted each time a request with an HTTP Expect: 100-continue is received. If this event is not listened for,
diff --git a/app/current/src/main/scala/io/scalajs/nodejs/https/package.scala b/app/current/src/main/scala/io/scalajs/nodejs/https/package.scala
index b5e946cea..6953001bf 100644
--- a/app/current/src/main/scala/io/scalajs/nodejs/https/package.scala
+++ b/app/current/src/main/scala/io/scalajs/nodejs/https/package.scala
@@ -16,7 +16,7 @@ package object https {
   /**
     * Https Extensions
     */
-  final implicit class HttpExtensions(val https: Https) extends AnyVal {
+  implicit final class HttpExtensions(val https: Https) extends AnyVal {
 
     /**
       * Like http.get() but for HTTPS.
diff --git a/app/current/src/main/scala/io/scalajs/nodejs/net/package.scala b/app/current/src/main/scala/io/scalajs/nodejs/net/package.scala
index d0b1ec69e..1dac4d796 100644
--- a/app/current/src/main/scala/io/scalajs/nodejs/net/package.scala
+++ b/app/current/src/main/scala/io/scalajs/nodejs/net/package.scala
@@ -17,7 +17,7 @@ package object net {
     * net.Server Events
     * @param server the given [[Server server]]
     */
-  implicit class ServerEvents(val server: Server) extends AnyVal {
+  implicit final class ServerEvents(val server: Server) extends AnyVal {
 
     /**
       * Emitted when a new connection is made. socket is an instance of net.Socket.
@@ -46,7 +46,7 @@ package object net {
     * net.Socket Extensions
     * @param socket the given [[Socket socket]]
     */
-  implicit class SocketExtensions(val socket: Socket) extends AnyVal {
+  implicit final class SocketExtensions(val socket: Socket) extends AnyVal {
 
     /////////////////////////////////////////////////////////////////////////////////
     //      Futures
diff --git a/app/current/src/main/scala/io/scalajs/nodejs/readline/Interface.scala b/app/current/src/main/scala/io/scalajs/nodejs/readline/Interface.scala
index 99b434604..e21026a3c 100644
--- a/app/current/src/main/scala/io/scalajs/nodejs/readline/Interface.scala
+++ b/app/current/src/main/scala/io/scalajs/nodejs/readline/Interface.scala
@@ -100,7 +100,7 @@ object Interface {
     * Readline Interface Events
     * @param readline the given [[Interface Readline Interface]]
     */
-  implicit class ReadlineEvents(val readline: Interface) extends AnyVal {
+  implicit final class ReadlineEvents(val readline: Interface) extends AnyVal {
 
     /**
       * Emitted when close() is called. Also emitted when the input stream receives its 'end' event.
diff --git a/app/current/src/main/scala/io/scalajs/nodejs/repl/REPLServer.scala b/app/current/src/main/scala/io/scalajs/nodejs/repl/REPLServer.scala
index 41c804b28..306b3383b 100644
--- a/app/current/src/main/scala/io/scalajs/nodejs/repl/REPLServer.scala
+++ b/app/current/src/main/scala/io/scalajs/nodejs/repl/REPLServer.scala
@@ -76,7 +76,7 @@ object REPLServer {
     * REPL Server Extensions
     * @param server the given [[REPLServer REPL Server]]
     */
-  final implicit class REPLServerExtensions[T <: REPLServer](val server: T) extends AnyVal {
+  implicit final class REPLServerExtensions[T <: REPLServer](val server: T) extends AnyVal {
 
     /**
       * Emitted when the user exits the REPL in any of the defined ways. Namely, typing .exit at the repl,
diff --git a/app/current/src/main/scala/io/scalajs/nodejs/repl/package.scala b/app/current/src/main/scala/io/scalajs/nodejs/repl/package.scala
index 823a519e6..cd4889d32 100644
--- a/app/current/src/main/scala/io/scalajs/nodejs/repl/package.scala
+++ b/app/current/src/main/scala/io/scalajs/nodejs/repl/package.scala
@@ -13,7 +13,7 @@ package object repl {
     * REPL Server events
     * @param server the given [[REPLServer instance]]
     */
-  final implicit class REPLServerEvents(val server: REPLServer) extends AnyVal {
+  implicit final class REPLServerEvents(val server: REPLServer) extends AnyVal {
 
     @inline
     def contextAs[T]: T = server.context.asInstanceOf[T]
@@ -47,7 +47,7 @@ package object repl {
     * <li>NODE_REPL_MODE</li>
     * </ul>
     */
-  final implicit class EnvironmentVariableOptions(private val env: process.Environment) extends AnyVal {
+  implicit final class EnvironmentVariableOptions(private val env: process.Environment) extends AnyVal {
 
     /**
       * When a valid path is given, persistent REPL history will be saved to the specified file rather
diff --git a/app/current/src/main/scala/io/scalajs/nodejs/timers/Immediate.scala b/app/current/src/main/scala/io/scalajs/nodejs/timers/Immediate.scala
index d2410b948..1cd285e9b 100644
--- a/app/current/src/main/scala/io/scalajs/nodejs/timers/Immediate.scala
+++ b/app/current/src/main/scala/io/scalajs/nodejs/timers/Immediate.scala
@@ -32,7 +32,7 @@ object Immediate {
     * Immediate Enrichment
     * @param immediate the given [[Immediate immediate]] handle
     */
-  implicit class ImmediateEnrichment(val immediate: Immediate) extends AnyVal {
+  implicit final class ImmediateEnrichment(val immediate: Immediate) extends AnyVal {
 
     @inline
     def clear(): Unit = clearImmediate(immediate)
diff --git a/app/current/src/main/scala/io/scalajs/nodejs/timers/Interval.scala b/app/current/src/main/scala/io/scalajs/nodejs/timers/Interval.scala
index dddde1a93..5217862ca 100644
--- a/app/current/src/main/scala/io/scalajs/nodejs/timers/Interval.scala
+++ b/app/current/src/main/scala/io/scalajs/nodejs/timers/Interval.scala
@@ -27,7 +27,7 @@ object Interval {
     * Interval Enrichment
     * @param handle the given [[Interval interval]] handle
     */
-  implicit class IntervalEnrichment(val handle: Interval) extends AnyVal {
+  implicit final class IntervalEnrichment(val handle: Interval) extends AnyVal {
 
     @inline
     def clear(): Unit = clearInterval(handle)
diff --git a/app/current/src/main/scala/io/scalajs/nodejs/timers/Timeout.scala b/app/current/src/main/scala/io/scalajs/nodejs/timers/Timeout.scala
index 62fca15c7..903167711 100644
--- a/app/current/src/main/scala/io/scalajs/nodejs/timers/Timeout.scala
+++ b/app/current/src/main/scala/io/scalajs/nodejs/timers/Timeout.scala
@@ -35,7 +35,7 @@ object Timeout {
     * Timeout Enrichment
     * @param handle the given [[Timeout timeout]] handle
     */
-  implicit class TimeoutEnrichment(val handle: Timeout) extends AnyVal {
+  implicit final class TimeoutEnrichment(val handle: Timeout) extends AnyVal {
 
     @inline
     def clear(): Unit = clearTimeout(handle)
diff --git a/app/current/src/main/scala/io/scalajs/nodejs/tty/package.scala b/app/current/src/main/scala/io/scalajs/nodejs/tty/package.scala
index 944c792cd..9d983d6ee 100644
--- a/app/current/src/main/scala/io/scalajs/nodejs/tty/package.scala
+++ b/app/current/src/main/scala/io/scalajs/nodejs/tty/package.scala
@@ -9,7 +9,7 @@ package object tty {
     * Write Stream Events
     * @param stream the given [[WriteStream stream]]
     */
-  implicit class WriteStreamEvents(val stream: WriteStream) extends AnyVal {
+  implicit final class WriteStreamEvents(val stream: WriteStream) extends AnyVal {
 
     /**
       * The 'resize' event is emitted whenever either of the writeStream.columns or writeStream.rows properties have
diff --git a/core/src/main/scala/io/scalajs/collection/JsCollection.scala b/core/src/main/scala/io/scalajs/collection/JsCollection.scala
index 1e4067116..cb921b2ce 100644
--- a/core/src/main/scala/io/scalajs/collection/JsCollection.scala
+++ b/core/src/main/scala/io/scalajs/collection/JsCollection.scala
@@ -40,7 +40,7 @@ object JsCollection {
     * JavaScript Collection Enrichment
     * @param collection the given [[JsCollection collection]]
     */
-  implicit class JsCollectionEnrichment[T](val collection: JsCollection[T]) extends AnyVal {
+  implicit final class JsCollectionEnrichment[T](val collection: JsCollection[T]) extends AnyVal {
 
     @inline
     def get(index: Int): Option[T] = Option(collection(index))
diff --git a/core/src/main/scala/io/scalajs/package.scala b/core/src/main/scala/io/scalajs/package.scala
index 128f11d7c..3043eb5ff 100644
--- a/core/src/main/scala/io/scalajs/package.scala
+++ b/core/src/main/scala/io/scalajs/package.scala
@@ -18,7 +18,7 @@ package object scalajs {
     * JSON Enrichment
     * @param json the given [[JSON]] object
     */
-  implicit class JSONEnrichment(val json: JSON) extends AnyVal {
+  implicit final class JSONEnrichment(val json: JSON) extends AnyVal {
 
     @inline
     def parseAs[T](text: String): T = json.parse(text).asInstanceOf[T]
diff --git a/core/src/main/scala/io/scalajs/util/DateHelper.scala b/core/src/main/scala/io/scalajs/util/DateHelper.scala
index 31fcca1ff..ee091f4ff 100644
--- a/core/src/main/scala/io/scalajs/util/DateHelper.scala
+++ b/core/src/main/scala/io/scalajs/util/DateHelper.scala
@@ -12,7 +12,7 @@ object DateHelper {
     * Date Enrichment
     * @param date0 the given [[js.Date date]]
     */
-  implicit class DateEnrichment(val date0: js.Date) extends AnyVal {
+  implicit final class DateEnrichment(private val date0: js.Date) extends AnyVal {
 
     @inline
     def +(duration: Duration) = new js.Date(date0.getTime() + duration.toMillis)
@@ -41,7 +41,7 @@ object DateHelper {
     * Duration Enrichment
     * @param duration the given [[Duration duration]]
     */
-  implicit class DurationEnrichment(val duration: Duration) extends AnyVal {
+  implicit final class DurationEnrichment(private val duration: Duration) extends AnyVal {
 
     @inline
     def +(date: js.Date) = new js.Date(date.getTime() + duration.toMillis)
diff --git a/core/src/main/scala/io/scalajs/util/JSONHelper.scala b/core/src/main/scala/io/scalajs/util/JSONHelper.scala
index cf4c09722..e951d2ffa 100644
--- a/core/src/main/scala/io/scalajs/util/JSONHelper.scala
+++ b/core/src/main/scala/io/scalajs/util/JSONHelper.scala
@@ -13,7 +13,7 @@ object JSONHelper {
     * JSON Conversions
     * @param value the given JavaScript value
     */
-  implicit class JSONConversionsToJson[T <: js.Any](val value: T) extends AnyVal {
+  implicit final class JSONConversionsToJson[T <: js.Any](val value: T) extends AnyVal {
 
     @inline
     def toJson: String = JSON.stringify(value)
@@ -27,7 +27,7 @@ object JSONHelper {
     * JSON Conversions
     * @param text the given text string
     */
-  implicit class JSONConversionFromJson(val text: String) extends AnyVal {
+  implicit final class JSONConversionFromJson(val text: String) extends AnyVal {
 
     @inline
     def fromJson[T <: js.Any]: T = JSON.parse(text).asInstanceOf[T]
diff --git a/core/src/main/scala/io/scalajs/util/JsUnderOrHelper.scala b/core/src/main/scala/io/scalajs/util/JsUnderOrHelper.scala
index f347d1668..7e803ef5e 100644
--- a/core/src/main/scala/io/scalajs/util/JsUnderOrHelper.scala
+++ b/core/src/main/scala/io/scalajs/util/JsUnderOrHelper.scala
@@ -12,7 +12,7 @@ object JsUnderOrHelper {
     * UndefOr Extensions
     * @param valueA the given [[js.UndefOr value]]
     */
-  implicit class UndefOrExtensions[T](val valueA: js.UndefOr[T]) extends AnyVal {
+  implicit final class UndefOrExtensions[T](private val valueA: js.UndefOr[T]) extends AnyVal {
 
     @inline def ?==(valueB: js.UndefOr[T]): Boolean = valueA.exists(valueB.contains)
 
@@ -40,7 +40,7 @@ object JsUnderOrHelper {
     * UndefOr Boolean Extensions
     * @param value the given [[js.UndefOr value]]
     */
-  implicit class UndefOrBoolExtensions(val value: js.UndefOr[Boolean]) extends AnyVal {
+  implicit final class UndefOrBoolExtensions(private val value: js.UndefOr[Boolean]) extends AnyVal {
 
     @inline
     def isTrue: Boolean = value.flat.contains(true)
@@ -51,7 +51,7 @@ object JsUnderOrHelper {
     * UndefOr Double Extensions
     * @param value the given [[js.UndefOr value]]
     */
-  implicit class UndefOrDoubleExtensions(val value: js.UndefOr[Double]) extends AnyVal {
+  implicit final class UndefOrDoubleExtensions(val value: js.UndefOr[Double]) extends AnyVal {
 
     @inline
     def orZero: Double = value.flat getOrElse 0.0
@@ -62,7 +62,7 @@ object JsUnderOrHelper {
     * UndefOr Integer Extensions
     * @param value the given [[js.UndefOr value]]
     */
-  implicit class UndefOrIntExtensions(val value: js.UndefOr[Int]) extends AnyVal {
+  implicit final class UndefOrIntExtensions(val value: js.UndefOr[Int]) extends AnyVal {
 
     @inline
     def orZero: Int = value.flat getOrElse 0
diff --git a/core/src/main/scala/io/scalajs/util/OptionHelper.scala b/core/src/main/scala/io/scalajs/util/OptionHelper.scala
index 232996b22..9be5b14c5 100644
--- a/core/src/main/scala/io/scalajs/util/OptionHelper.scala
+++ b/core/src/main/scala/io/scalajs/util/OptionHelper.scala
@@ -13,7 +13,7 @@ object OptionHelper {
     * Option Extensions
     * @param valueA the given [[Option optional value]]
     */
-  implicit class OptionExtensions[T](val valueA: Option[T]) extends AnyVal {
+  implicit final class OptionExtensions[T](val valueA: Option[T]) extends AnyVal {
 
     @inline def ?==(valueB: js.UndefOr[T]): Boolean = valueA.exists(v => valueB.exists(_ == v))
 
@@ -39,7 +39,7 @@ object OptionHelper {
     * Option Boolean Extensions
     * @param value the given [[Option value]]
     */
-  implicit class OptionBoolExtensions(val value: Option[Boolean]) extends AnyVal {
+  implicit final class OptionBoolExtensions(val value: Option[Boolean]) extends AnyVal {
 
     @inline def isTrue: Boolean = value.contains(true)
 
@@ -49,7 +49,7 @@ object OptionHelper {
     * Option Double Extensions
     * @param value the given [[Option value]]
     */
-  implicit class OptionDoubleExtensions(val value: Option[Double]) extends AnyVal {
+  implicit final class OptionDoubleExtensions(val value: Option[Double]) extends AnyVal {
 
     @inline def orZero: Double = value getOrElse 0.0
 
@@ -59,7 +59,7 @@ object OptionHelper {
     * Option Integer Extensions
     * @param value the given [[Option value]]
     */
-  implicit class OptionIntExtensions(val value: Option[Int]) extends AnyVal {
+  implicit final class OptionIntExtensions(val value: Option[Int]) extends AnyVal {
 
     @inline def orZero: Int = value getOrElse 0
 
diff --git a/core/src/main/scala/io/scalajs/util/PromiseHelper.scala b/core/src/main/scala/io/scalajs/util/PromiseHelper.scala
index 8649d8b52..07dd11315 100644
--- a/core/src/main/scala/io/scalajs/util/PromiseHelper.scala
+++ b/core/src/main/scala/io/scalajs/util/PromiseHelper.scala
@@ -273,7 +273,7 @@ object PromiseHelper {
     * @param task the given [[Future task]]
     * @tparam T the return type of the task
     */
-  implicit class TimeExtensions[T](val task: Future[T]) extends AnyVal {
+  implicit final class TimeExtensions[T](val task: Future[T]) extends AnyVal {
 
     @inline
     def withTimer(action: String, showHeader: Boolean = false)(implicit ec: ExecutionContext): Future[T] = {
diff --git a/core/src/main/scala/io/scalajs/util/ScalaJsHelper.scala b/core/src/main/scala/io/scalajs/util/ScalaJsHelper.scala
index a49b4e5b2..3e31601bf 100644
--- a/core/src/main/scala/io/scalajs/util/ScalaJsHelper.scala
+++ b/core/src/main/scala/io/scalajs/util/ScalaJsHelper.scala
@@ -30,7 +30,7 @@ object ScalaJsHelper {
     * js.Dynamic to Value Extensions
     * @param obj the given [[js.Dynamic object]]
     */
-  implicit class JsAnyExtensions(val obj: js.Any) extends AnyVal {
+  implicit final class JsAnyExtensions(val obj: js.Any) extends AnyVal {
 
     @inline
     def asUndefOr[T]: js.UndefOr[T] = obj.asInstanceOf[js.UndefOr[T]].flat
@@ -61,7 +61,7 @@ object ScalaJsHelper {
     * js.Array Extensions
     * @param array the given [[js.Array array]]
     */
-  implicit class JsArrayExtensions[A](val array: js.Array[A]) extends AnyVal {
+  implicit final class JsArrayExtensions[A](val array: js.Array[A]) extends AnyVal {
 
     @inline
     def indexWhereOpt(f: A => Boolean): Option[Int] = array.indexWhere(f) match {
@@ -83,7 +83,7 @@ object ScalaJsHelper {
     * js.Dictionary Extensions
     * @param dict the given [[js.Dictionary dictionary]]
     */
-  implicit class JsDictionaryExtensions[A](val dict: js.Dictionary[A]) extends AnyVal {
+  implicit final class JsDictionaryExtensions[A](val dict: js.Dictionary[A]) extends AnyVal {
 
     @inline
     def replaceWith(items: (String, A)*): Unit = {