diff --git a/kernel/taskstats.c b/kernel/taskstats.c
index a09a549..e19ce14 100644
--- a/kernel/taskstats.c
+++ b/kernel/taskstats.c
@@ -304,7 +304,7 @@
 			listeners = &per_cpu(listener_array, cpu);
 			down_write(&listeners->sem);
 			list_for_each_entry(s2, &listeners->list, list) {
-				if (s2->pid == pid)
+				if (s2->pid == pid && s2->valid)
 					goto exists;
 			}
 			list_add(&s->list, &listeners->list);