1 files changed, 6 insertions, 2 deletions
diff --git a/gnu/classpath/jdwp/processor/ThreadGroupReferenceCommandSet.java b/gnu/classpath/jdwp/processor/ThreadGroupReferenceCommandSet.java
index ba36251f6..103199a2b 100644
--- a/gnu/classpath/jdwp/processor/ThreadGroupReferenceCommandSet.java
+++ b/gnu/classpath/jdwp/processor/ThreadGroupReferenceCommandSet.java
@@ -103,8 +103,12 @@ public class ThreadGroupReferenceCommandSet
     ObjectId oid = idMan.readObjectId(bb);
     ThreadGroup group = (ThreadGroup) oid.getObject();
     ThreadGroup parent = group.getParent();
-    ObjectId parentId = idMan.getObjectId(parent);
-    parentId.write(os);
+    if (parent == null) {
+    	os.writeLong(0L);
+    } else {
+    	ObjectId parentId = idMan.getObjectId(parent);
+    	parentId.write(os);   	
+    }
   }
 
   private void executeChildren(ByteBuffer bb, DataOutputStream os)