diff --git a/ChangeLog b/ChangeLog
index c02ced91a5..15e9e1c7b5 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Oct 16 22:43:12 2014  Tanaka Akira  <akr@fsij.org>
+
+	* vm_backtrace.c (id2str): Fix a variable name.
+	  [ruby-dev:48642] [Bug #10389]
+
 Thu Oct 16 20:01:26 2014  Tanaka Akira  <akr@fsij.org>
 
 	* test/ruby/envutil.rb (assert_pattern_list): Show number of matched
diff --git a/vm_backtrace.c b/vm_backtrace.c
index 63b5fc371a..70db469074 100644
--- a/vm_backtrace.c
+++ b/vm_backtrace.c
@@ -27,7 +27,7 @@ static VALUE
 id2str(ID id)
 {
     VALUE str = rb_id2str(id);
-    if (!id) return Qnil;
+    if (!str) return Qnil;
     return str;
 }
 #define rb_id2str(id) id2str(id)