diff --git a/build.gradle.kts b/build.gradle.kts
index 8144c7d..9117c21 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -52,7 +52,9 @@ subprojects {
             // The following lines are needed at least for the current version of proguard
             dontwarn("java.**")
             val homeDir = System.getProperty("java.home") as String
-            libraryjars("$homeDir/lib/rt.jar")
+            if (JavaVersion.current().isJava9Compatible()) {
+                libraryjars("$homeDir/jmods/java.base.jmod")
+            } else libraryjars("$homeDir/lib/rt.jar")
             // Note: dontpreverify() should NOT be used, it will cause errors at runtime
             useuniqueclassmembernames()
             optimizations("method/inlining/*, code/allocation/variable, class/merging/vertical, class/merging/horizontal, code/removal/advanced, code/simplification/branch, code/merging")