diff --git a/actor/src/main/scala-jdk-9/org/apache/pekko/dispatch/PekkoJdk9ForkJoinPool.scala b/actor/src/main/scala-jdk-9/org/apache/pekko/dispatch/PekkoJdk9ForkJoinPool.scala
index 8564f3e50bc..917b3e6adc5 100644
--- a/actor/src/main/scala-jdk-9/org/apache/pekko/dispatch/PekkoJdk9ForkJoinPool.scala
+++ b/actor/src/main/scala-jdk-9/org/apache/pekko/dispatch/PekkoJdk9ForkJoinPool.scala
@@ -17,6 +17,7 @@
 
 package org.apache.pekko.dispatch
 
+import org.apache.pekko.annotation.InternalApi
 import org.apache.pekko.dispatch.ForkJoinExecutorConfigurator.PekkoForkJoinTask
 
 import java.util.concurrent.{ ForkJoinPool, ForkJoinTask, TimeUnit }
@@ -27,6 +28,7 @@ import java.util.concurrent.{ ForkJoinPool, ForkJoinTask, TimeUnit }
  * An alternative version of [[ForkJoinExecutorConfigurator.PekkoForkJoinPool]]
  * that supports the `maximumPoolSize` feature available in [[java.util.concurrent.ForkJoinPool]] in JDK9+.
  */
+@InternalApi
 private[dispatch] final class PekkoJdk9ForkJoinPool(
     parallelism: Int,
     threadFactory: ForkJoinPool.ForkJoinWorkerThreadFactory,
diff --git a/actor/src/main/scala/org/apache/pekko/dispatch/ForkJoinPoolConstants.scala b/actor/src/main/scala/org/apache/pekko/dispatch/ForkJoinPoolConstants.scala
index 2b59b9e1104..7643c2d2deb 100644
--- a/actor/src/main/scala/org/apache/pekko/dispatch/ForkJoinPoolConstants.scala
+++ b/actor/src/main/scala/org/apache/pekko/dispatch/ForkJoinPoolConstants.scala
@@ -18,6 +18,6 @@
 package org.apache.pekko.dispatch
 
 private[dispatch] object ForkJoinPoolConstants {
-  val MaxCap: Int = 0x7FFF // 32767
-  val DefaultKeepAlive: Long = 60000
+  final val MaxCap: Int = 0x7FFF // 32767
+  final val DefaultKeepAlive: Long = 60000
 }