diff --git a/ChangeLog b/ChangeLog
index 51f3e49a24..84f708ab28 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Jul 19 19:24:14 2007  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* eval.c (get_backtrace): check the result more.
+	  [ruby-dev:31261] [ruby-bugs-12398]
+
 Thu Jul 19 14:38:45 2007  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* bignum.c (rb_big_lshift, rb_big_rshift): separated functions
diff --git a/error.c b/error.c
index 44e709276f..608d1fa558 100644
--- a/error.c
+++ b/error.c
@@ -488,14 +488,14 @@ static VALUE
 exc_backtrace(exc)
     VALUE exc;
 {
-    ID bt = rb_intern("bt");
+    static ID bt;
 
-    if (!rb_ivar_defined(exc, bt)) return Qnil;
-    return rb_ivar_get(exc, bt);
+    if (!bt) bt = rb_intern("bt");
+    return rb_attr_get(exc, bt);
 }
 
-static VALUE
-check_backtrace(bt)
+VALUE
+rb_check_backtrace(bt)
     VALUE bt;
 {
     long i;
@@ -532,7 +532,7 @@ exc_set_backtrace(exc, bt)
     VALUE exc;
     VALUE bt;
 {
-    return rb_iv_set(exc, "bt", check_backtrace(bt));
+    return rb_iv_set(exc, "bt", rb_check_backtrace(bt));
 }
 
 /*
diff --git a/eval.c b/eval.c
index 6e3b2a38b4..c896ed08bd 100644
--- a/eval.c
+++ b/eval.c
@@ -1197,6 +1197,8 @@ error_pos()
     }
 }
 
+VALUE rb_check_backtrace(VALUE);
+
 static VALUE
 get_backtrace(info)
     VALUE info;
@@ -1204,7 +1206,7 @@ get_backtrace(info)
     if (NIL_P(info)) return Qnil;
     info = rb_funcall(info, rb_intern("backtrace"), 0);
     if (NIL_P(info)) return Qnil;
-    return rb_check_array_type(info);
+    return rb_check_backtrace(info);
 }
 
 static void