diff --git a/executer/user/mcexec.c b/executer/user/mcexec.c
index 149f9b24..1be6c220 100644
--- a/executer/user/mcexec.c
+++ b/executer/user/mcexec.c
@@ -3027,8 +3027,9 @@ create_tracer()
 			term_param[1] = uti_desc->tid;
 			term_param[3] = uti_desc->key;
 			code = st;
-			if (exited == 2 || // exit_group
-			    WIFSIGNALED(st)) {
+			/* exit_group case. Note that killing-signal kills mcexec and tracer in terminate(),
+			   so this won't be reached. */
+			if (exited == 2) { 
 				code |= 0x0000000100000000;
 			}
 			term_param[2] = code;
diff --git a/kernel/syscall.c b/kernel/syscall.c
index cfe0c076..d8173bd7 100644
--- a/kernel/syscall.c
+++ b/kernel/syscall.c
@@ -9123,13 +9123,13 @@ util_thread(struct uti_attr *arg)
 	kfree(uti_clv);
 
 	if (rc >= 0) {
-		if (rc & 0x10000007f) { // exit_group || signal
-			dkprintf("%s: exit_group || signal\n", __FUNCTION__);
+		if (rc & 0x100000000) { /* exit_group */
+			dkprintf("%s: exit_group, tid=%d,rc=%lx\n", __FUNCTION__, thread->tid, rc);
 			thread->proc->nohost = 1;
 			terminate((rc >> 8) & 255, rc & 255);
-		}
-		else {
-			dkprintf("%s: !exit_group && !signal\n", __FUNCTION__);
+		} else {
+			/* tracer has detected exit or killed by signal */
+			dkprintf("%s: exit, pid=%d,tid=%d,rc=%lx\n", __FUNCTION__, thread->proc->pid, thread->tid, rc);
 			request.number = __NR_sched_setaffinity;
 			request.args[0] = 1;
 			request.args[1] = free_address;