diff --git a/promagent-framework/promagent-loader/README.md b/promagent-framework/promagent-loader/README.md
index 09af0aa..802f4f8 100644
--- a/promagent-framework/promagent-loader/README.md
+++ b/promagent-framework/promagent-loader/README.md
@@ -7,7 +7,9 @@ Experimental tool for loading the promagent into an existing JVM. Usage:
 java -cp $JAVA_HOME/lib/tools.jar:/path/to/promagent-loader.jar io.promagent.loader.PromagentLoader -agent /path/to/promagent.jar -port 9300 -pid <pid>
 ```
 
-The JAR file `$JAVA_HOME/lib/tools.jar` must exist. It is part of JDK 8. With JDK 9 or higher, it might be possible to use the promagent-loader without this external dependency, because the classes were moved into the runtime.
+The `promagent-loader` uses OpenJDK API and will probably not work with other Java VMs.
+
+With JDK 8 or earlier, the file `$JAVA_HOME/lib/tools.jar` must exist. With JDK 9 or higher, the loader runs without this external dependency, because the classes have been moved into the Java runtime.
 
 The `/path/to/promagent.jar` must be an absolute path, not a relative path.