diff --git a/ChangeLog b/ChangeLog
index 63c2524647..a99751cf5b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Apr 24 00:25:39 2012  Yusuke Endoh  <mame@tsg.ne.jp>
+
+	* thread.c (rb_check_deadlock): refine an error message of deadlock
+	  detection.  [ruby-core:44336] [Bug #6288]
+
 Tue Apr 24 00:14:42 2012  Yusuke Endoh  <mame@tsg.ne.jp>
 
 	* parse.y (primary): remove wrong "fixpos" that caused incorrect
diff --git a/thread.c b/thread.c
index 1fcdf824f9..7383a886f6 100644
--- a/thread.c
+++ b/thread.c
@@ -4731,7 +4731,7 @@ rb_check_deadlock(rb_vm_t *vm)
     if (!found) {
 	VALUE argv[2];
 	argv[0] = rb_eFatal;
-	argv[1] = rb_str_new2("deadlock detected");
+	argv[1] = rb_str_new2("No live threads left. Deadlock?");
 #ifdef DEBUG_DEADLOCK_CHECK
 	printf("%d %d %p %p\n", vm->living_threads->num_entries, vm->sleeper, GET_THREAD(), vm->main_thread);
 	st_foreach(vm->living_threads, debug_i, (st_data_t)0);