diff --git a/ChangeLog b/ChangeLog
index 17686d1b0a..7e18ff7d8e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Fri Jan 29 22:49:21 2010  Yusuke Endoh  <mame@tsg.ne.jp>
+
+	* lib/getoptlong.rb (set_options): ensure that the type of argument is
+	  Array, restoring this check that was deleted at r10239.  This caused
+	  rubyspec error.
+
 Fri Jan 29 12:59:33 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* configure.in (mingw): needs $(DEFFILE) for extension libraries.
diff --git a/lib/getoptlong.rb b/lib/getoptlong.rb
index 2d3b617d6b..7bd9ee55cc 100644
--- a/lib/getoptlong.rb
+++ b/lib/getoptlong.rb
@@ -282,8 +282,11 @@ class GetoptLong
     @canonical_names.clear
     @argument_flags.clear
 
-    arguments.each do |*arg|
-      arg = arg.first # TODO: YARV Hack
+    arguments.each do |arg|
+      if !arg.is_a?(Array)
+       raise ArgumentError, "the option list contains non-Array argument"
+      end
+
       #
       # Find an argument flag and it set to `argument_flag'.
       #