diff --git a/README.md b/README.md
index 1033f9135c..5f5e2256d9 100644
--- a/README.md
+++ b/README.md
@@ -84,15 +84,19 @@ There are more build options available as well. For more information refer to [C
 
 To build Hibernate Validator with JDK 9, export the following environment variable:
 
-    export MAVEN_OPTS="--add-modules java.annotations.common,java.xml.bind --add-opens=java.base/java.security=ALL-UNNAMED --add-opens=java.base/java.io=ALL-UNNAMED --add-opens=java.base/java.lang=ALL-UNNAMED"
+    export MAVEN_OPTS="--add-modules java.annotations.common,java.xml.bind --add-opens=java.base/java.security=ALL-UNNAMED --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED"
 
 Then the build can be started like this:
 
-    mvn -s settings-example.xml clean install -DdisableDocumentationBuild=true -DdisableDistributionBuild
+    mvn -s settings-example.xml clean install
+
+Also the OSGi integration tests will fail on Java 9 currently, hence the "osgi" module is excluded automatically when building on JDK 9. We are waiting for the release of Karaf 4.1.0.
 
-The documentation and distribution modules are known to not work on Java 9 for the time being, hence they need to be excluded.
-Also the integration tests on WildFly will fail on Java 9 currently, hence this "integration" module is excluded automatically when building on JDK 9.
+Here are the reasons why we added the various --add-opens options:
 
+ * java.security: required by wildfly-maven-plugin:execute-commands (for the WildFly integration tests and the TCK runner running in container mode)
+ * java.lang: required by JRuby for Asciidoc processing
+ * java.util: required by the gmavenplus script used to start WildFly
 
 ## Continuous Integration