diff --git a/ChangeLog b/ChangeLog
index 6a5b079d28..4906f11af3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+Thu Aug  4 20:19:11 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
+
+	* error.c (report_bug): use a small message buffer instead of BUFSIZ.
+	  It is needed for avoiding nested SIGSEGV on Linux.
+	  Note: BUFSIZ is not proper buffer size. It's unrelated with maximum
+	  filename length. :-/
+	  [Bug #5139] [ruby-dev:44315]
+
 Thu Aug  4 16:08:45 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* tool/rbinstall.rb (gem): install all gemspecs under lib and ext.
diff --git a/error.c b/error.c
index 834eede8af..646fb16232 100644
--- a/error.c
+++ b/error.c
@@ -251,9 +251,10 @@ rb_warn_m(int argc, VALUE *argv, VALUE exc)
 static void
 report_bug(const char *file, int line, const char *fmt, va_list args)
 {
-    char buf[BUFSIZ];
+    /* SIGSEGV handler might have a very small stack. Thus we need to use it carefully. */
+    char buf[256];
     FILE *out = stderr;
-    int len = err_position_0(buf, BUFSIZ, file, line);
+    int len = err_position_0(buf, 256, file, line);
 
     if ((ssize_t)fwrite(buf, 1, len, out) == (ssize_t)len ||
 	(ssize_t)fwrite(buf, 1, len, (out = stdout)) == (ssize_t)len) {