diff --git a/ChangeLog b/ChangeLog
index 8e2cc6b715..cc72982085 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,7 @@
-Sat Jul 14 16:16:42 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+Sat Jul 14 16:16:48 2012  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* lib/test/unit.rb (Test::Unit::Runner#_run_parallel): use
+	  Array#uniq!.
 
 	* lib/test/unit.rb (Test::Unit::Runner#deal): deal tasks to workers.
 
diff --git a/lib/test/unit.rb b/lib/test/unit.rb
index fbeceb9e54..e8afbbcaa2 100644
--- a/lib/test/unit.rb
+++ b/lib/test/unit.rb
@@ -632,12 +632,7 @@ module Test
           end
           unless @warnings.empty?
             warn ""
-            ary = []
-            @warnings.reject! do |w|
-              r = ary.include?(w[1].message)
-              ary << w[1].message
-              r
-            end
+            @warnings.uniq! {|w| w[1].message}
             @warnings.each do |w|
               warn "#{w[0]}: #{w[1].message} (#{w[1].class})"
             end