diff --git a/activesupport/test/core_ext/time_ext_test.rb b/activesupport/test/core_ext/time_ext_test.rb
index 69f7e82585..955de05a51 100644
--- a/activesupport/test/core_ext/time_ext_test.rb
+++ b/activesupport/test/core_ext/time_ext_test.rb
@@ -114,13 +114,13 @@ class TimeExtCalculationsTest < ActiveSupport::TestCase
     assert_equal Rational(1, 1_000_000_000), time.sec_fraction
 
     time = Time.utc(2016, 4, 23, 0, 0, 0.000_000_001)
-    assert_equal Rational(1, 1_000_000_000), time.sec_fraction
+    assert_equal 0.000_000_001.to_r, time.sec_fraction
 
     time = Time.utc(2016, 4, 23, 0, 0, 0, Rational(1, 1_000))
     assert_equal Rational(1, 1_000_000_000), time.sec_fraction
 
     time = Time.utc(2016, 4, 23, 0, 0, 0, 0.001)
-    assert_equal Rational(1, 1_000_000_000), time.sec_fraction
+    assert_equal 0.001.to_r / 1000000, time.sec_fraction
   end
 
   def test_beginning_of_day