diff --git a/test/ruby/test_math.rb b/test/ruby/test_math.rb
index 4d819d7..76d6d1c 100644
--- a/test/ruby/test_math.rb
+++ b/test/ruby/test_math.rb
@@ -146,10 +146,15 @@ class TestMath < Test::Unit::TestCase
     assert_equal(1.0/0, Math.log(1.0/0))
     assert_nothing_raised { assert_infinity(-Math.log(+0.0)) }
     assert_nothing_raised { assert_infinity(-Math.log(-0.0)) }
-    assert_raise(Math::DomainError) { Math.log(-1.0) }
     assert_raise(TypeError) { Math.log(1,nil) }
+    assert_raise(Math::DomainError) { Math.log(-1.0) }
     assert_raise(Math::DomainError, '[ruby-core:62309] [ruby-Bug #9797]') { Math.log(1.0, -1.0) }
-    assert_nothing_raised { assert_nan(Math.log(0.0, 0.0)) }
+    assert_raise(Math::DomainError) { Math.log(0.0, 0.0) }
+    assert_raise(Math::DomainError) { Math.log(1.0, 0.0) }
+    assert_raise(Math::DomainError) { Math.log(2.0, 0.0) }
+    assert_raise(Math::DomainError) { Math.log(0.0, 1.0) }
+    assert_raise(Math::DomainError) { Math.log(1.0, 1.0) }
+    assert_raise(Math::DomainError) { Math.log(2.0, 1.0) }
   end

   def test_log2