diff --git a/core/src/main/java/net/adoptopenjdk/icedteaweb/jvm/JvmUtils.java b/core/src/main/java/net/adoptopenjdk/icedteaweb/jvm/JvmUtils.java
index 4c536b437..e629f9ff3 100644
--- a/core/src/main/java/net/adoptopenjdk/icedteaweb/jvm/JvmUtils.java
+++ b/core/src/main/java/net/adoptopenjdk/icedteaweb/jvm/JvmUtils.java
@@ -187,7 +187,11 @@ private static String[] getValidVMArguments() {
                 "-XX:+ScavengeBeforeFullGC",
                 "-XX:-ScavengeBeforeFullGC",
                 "-XX:+UseParallelScavenge",
-                "-XX:-UseParallelScavenge"
+                "-XX:-UseParallelScavenge",
+                "-XX:+UseParNewGC",
+                "-XX:+PrintFlagsFinal",
+                "-XX:+PrintCommandLineFlags",
+                "-XX:+PrintGCDateStamps"
         };
     }
 
@@ -197,6 +201,7 @@ private static String[] getValidVMArguments() {
      * <p>
      * Based on
      * https://docs.oracle.com/javase/8/docs/technotes/guides/javaws/developersguide/syntax.html#secure-property
+     * https://docs.oracle.com/en/java/javase/21/docs/specs/man/java.html
      */
     private static String[] getValidStartingVMArguments() {
         return new String[]{
@@ -217,6 +222,7 @@ private static String[] getValidStartingVMArguments() {
                 "-XX:MinHeapFreeRatio", /* heap free percentage (default 40) */
                 "-XX:UseSerialGC", /* use serial garbage collection */
                 "-XX:-UseSerialGC",
+                "-XX:+UseSerialGC",
                 "-XX:ThreadStackSize", /* thread stack size (in KB) */
                 "-XX:MaxInlineSize", /* set max num of bytecodes to inline */
                 "-XX:ReservedCodeCacheSize", /* Reserved code cache size (bytes) */
@@ -240,6 +246,9 @@ private static String[] getValidStartingVMArguments() {
                 "-XX:GCHeapFreeLimit",
                 "-XX:+UseParNewGC",
                 "-XX:+CMSParallelRemarkEnabled",
+                "-XX:+UseZGC",
+                "-XX:+ZGenerational",
+                "-XX:HeapDumpPath",
                 "-XX:InitialRAMPercentage", /* The initial heap size as percentage of total memory, conflicts with Xms */
                 "-XX:MinRAMPercentage", /* Sets the max heap size of RAM as a percentage before looking at other heuristics like MaxRAMPercentage. This is primarily useful for low memory environments (<100m) */
                 "-XX:MaxRAMPercentage", /* Sets the max heap size of RAM as a percentage */
@@ -289,6 +298,7 @@ private static String[] getValidSecureProperties() {
                 "http.maxRedirects",
                 "http.auth.digest.validateProxy",
                 "http.auth.digest.validateServer",
+                "user.timezone",
                 // https://news.kynosarges.org/2019/03/24/swing-high-dpi-properties/
                 "sun.java2d.uiScale.enabled",
                 "sun.java2d.win.uiScaleX",