src/jdk.jlink/share/classes/jdk/tools/jlink/internal/JlinkTask.java

@@ -250,13 +250,21 @@
                 postProcessOnly(taskHelper.getExistingImage());
                 return EXIT_OK;
             }
 
             if (options.modulePath.isEmpty()) {
+                // no --module-path specified - try to set $JAVA_HOME/jmods if that exists
+                Path jmods = JlinkConfiguration.getDefaultModulePath();
+                if (jmods != null) {
+                    options.modulePath.add(jmods);
+                }
+
+                if (options.modulePath.isEmpty()) {
                 throw taskHelper.newBadArgs("err.modulepath.must.be.specified")
                                 .showUsage(true);
             }
+            }
 
             JlinkConfiguration config = initJlinkConfig();
             if (options.suggestProviders) {
                 suggestProviders(config, remaining);
             } else {