diff --git a/ChangeLog b/ChangeLog
index ea8e3e3e3c..c5310a033f 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Fri Sep 19 10:47:03 2014  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* test/ruby/test_math.rb (TestMath#assert_infinity): Float#finite?
+	  returns true also for NaN, so use Float#infinite? instead.
+	  [ruby-core:65117] [Feature #10261]
+
 Fri Sep 19 05:36:16 2014  Eric Wong  <e@80x24.org>
 
 	* NEWS: note --with-jemalloc option [ci skip]
diff --git a/test/ruby/test_math.rb b/test/ruby/test_math.rb
index 4d819d71a1..c4d0ff93f2 100644
--- a/test/ruby/test_math.rb
+++ b/test/ruby/test_math.rb
@@ -3,7 +3,7 @@ require 'test/unit'
 class TestMath < Test::Unit::TestCase
   def assert_infinity(a, *rest)
     rest = ["not infinity: #{a.inspect}"] if rest.empty?
-    assert_not_predicate(a, :finite?, *rest)
+    assert_predicate(a, :infinite?, *rest)
   end
 
   def assert_nan(a, *rest)