diff --git a/ChangeLog b/ChangeLog
index 7bddc012fb..84bf7b09dd 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sat May 16 17:57:39 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* ext/dl/lib/dl/callback.rb (DL#remove_callback_internal): ignore
+	  unbound function.  [ruby-dev:38474]
+
 Sat May 16 17:51:11 2009  Kouhei Sutou  <kou@cozmixng.org>
 
 	* sample/rss/rss_recent.rb, sample/rss/list_description.rb: use
diff --git a/ext/dl/lib/dl/callback.rb b/ext/dl/lib/dl/callback.rb
index d0b2c7a819..c8daaf6322 100644
--- a/ext/dl/lib/dl/callback.rb
+++ b/ext/dl/lib/dl/callback.rb
@@ -48,7 +48,7 @@ module DL
         }
       }
     end
-    if( proc_entry[ctype][index] )
+    if( index and proc_entry[ctype][index] )
       proc_entry[ctype][index] = nil
       return true
     else