--- a/src/share/vm/runtime/arguments.cpp	Thu Mar 21 14:11:13 2013 +0100
+++ b/src/share/vm/runtime/arguments.cpp	Fri Mar 22 12:08:24 2013 +0100
@@ -2096,6 +2096,18 @@
     // This prevents the flag being set to true by set_ergonomics_flags()
     FLAG_SET_CMDLINE(bool, UseCompressedKlassPointers, false);
   }
+  if (UseG1GC) {
+      if (IgnoreUnrecognizedVMOptions) {
+        warning("UseG1GC is still experimental in Graal, use SerialGC instead ");
+        FLAG_SET_CMDLINE(bool, UseG1GC, true);
+      } else {
+        warning("UseG1GC is still experimental in Graal, use SerialGC instead ");
+        status = true;
+      }
+    } else {
+      // This prevents the flag being set to true by set_ergonomics_flags()
+      FLAG_SET_CMDLINE(bool, UseG1GC, false);
+    }
 
   if (!ScavengeRootsInCode) {
       warning("forcing ScavengeRootsInCode non-zero because Graal is enabled");