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@@ -16,6 +16,10 @@ Demo data can be downloaded here: [ModuleViewerDemoData](ModuleViewerDemoData).
 
 ## Running ModuleViewer ######
 
+ModuleViewer is a Java application. Make sure you have installed a [Java Runtime Environment][java].
+
+[java]: https://www.java.com/en/download/
+
 ### Start ModuleViewer ####
 
 [![Java WebStart](docs/webstart.gif)](http://bioinformatics.psb.ugent.be/webtools/moduleviewer/launch.jnlp)