diff --git a/src/java.instrument/share/classes/java/lang/instrument/Instrumentation.java b/src/java.instrument/share/classes/java/lang/instrument/Instrumentation.java
index d4719ea6f5b..d92180bef10 100644
--- a/src/java.instrument/share/classes/java/lang/instrument/Instrumentation.java
+++ b/src/java.instrument/share/classes/java/lang/instrument/Instrumentation.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2003, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -65,6 +65,9 @@ import java.util.jar.JarFile;
  * <p>
  * Once an agent acquires an <code>Instrumentation</code> instance,
  * the agent may call methods on the instance at any time.
+ * <p>
+ * @apiNote This interface is not intended to be implemented outside of
+ * the java.instrument module.
  *
  * @since   1.5
  */