diff --git a/test/-ext-/integer/test_my_integer.rb b/test/-ext-/integer/test_my_integer.rb
index 1b6f8489f8..0dfa234921 100644
--- a/test/-ext-/integer/test_my_integer.rb
+++ b/test/-ext-/integer/test_my_integer.rb
@@ -8,19 +8,13 @@ class Test_MyInteger < Test::Unit::TestCase
       Bug::Integer::MyInteger.new.to_f
     end
 
-    begin
-      Bug::Integer::MyInteger.class_eval do
-        def to_f
-        end
+    int = Class.new(Bug::Integer::MyInteger) do
+      def to_f
       end
+    end
 
-      assert_nothing_raised do
-        Bug::Integer::MyInteger.new.to_f
-      end
-    ensure
-      Bug::Integer::MyInteger.class_eval do
-        remove_method :to_f
-      end
+    assert_nothing_raised do
+      int.new.to_f
     end
   end
 
@@ -29,20 +23,14 @@ class Test_MyInteger < Test::Unit::TestCase
       Bug::Integer::MyInteger.new <=> 0
     end
 
-    begin
-      Bug::Integer::MyInteger.class_eval do
-        def <=>(other)
-          0
-        end
+    int = Class.new(Bug::Integer::MyInteger) do
+      def <=>(other)
+        0
       end
+    end
 
-      assert_nothing_raised do
-        Bug::Integer::MyInteger.new <=> 0
-      end
-    ensure
-      Bug::Integer::MyInteger.class_eval do
-        remove_method :<=>
-      end
+    assert_nothing_raised do
+      int.new <=> 0
     end
   end
 end