diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index b0ace60..7c76f2f 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -169,7 +169,7 @@
 	retval = -EPERM;
 	if (task->pid <= 1)
 		goto out;
-	if (task->tgid == current->tgid)
+	if (same_thread_group(task, current))
 		goto out;
 
 repeat: