diff --git a/ChangeLog b/ChangeLog
index 7f7c769d0d..08d9cad408 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Fri Jul  8 15:53:31 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* error.c (rb_bug): get rid of segfault after all threads
+	  disposed.
+
 Fri Jul  8 15:01:06 2011  NAKAMURA Usaku  <usa@ruby-lang.org>
 
 	* ext/openssl/ossl.h: include openssl/e_os2.h before checking the
diff --git a/error.c b/error.c
index 5bceb7df5b..ce959fc221 100644
--- a/error.c
+++ b/error.c
@@ -265,9 +265,16 @@ void
 rb_bug(const char *fmt, ...)
 {
     va_list args;
+    const char *file = NULL;
+    int line = 0;
+
+    if (GET_THREAD()) {
+	file = rb_sourcefile();
+	line = rb_sourceline();
+    }
 
     va_start(args, fmt);
-    report_bug(rb_sourcefile(), rb_sourceline(), fmt, args);
+    report_bug(file, line, fmt, args);
     va_end(args);
 
 #if defined(_WIN32) && defined(RT_VER) && RT_VER >= 80