diff --git a/test/ruby/test_float.rb b/test/ruby/test_float.rb
index dfd1b5bb7e..f3224fface 100644
--- a/test/ruby/test_float.rb
+++ b/test/ruby/test_float.rb
@@ -11,6 +11,8 @@ class TestFloat < Test::Unit::TestCase
     assert_equal(3, 2.6.round)
     assert_equal(-2, (-2.4).truncate)
     assert((13.4 % 1 - 0.4).abs < 0.0001)
+    assert_equal(36893488147419111424,
+                 36893488147419107329.0.to_i)
     assert_equal("36893488147419111424",
                  sprintf("%20.0f", 36893488147419107329.0))
   end