diff --git a/test/ruby/test_time.rb b/test/ruby/test_time.rb
index 8718dbc327..d7e736de3a 100644
--- a/test/ruby/test_time.rb
+++ b/test/ruby/test_time.rb
@@ -109,21 +109,21 @@ class TestTime < Test::Unit::TestCase
   end
 
   def test_at
-    assert_equal(100000, Time.at("0.1").usec)
-    assert_equal(10000, Time.at("0.01").usec)
-    assert_equal(1000, Time.at("0.001").usec)
-    assert_equal(100, Time.at("0.0001").usec)
-    assert_equal(10, Time.at("0.00001").usec)
-    assert_equal(1, Time.at("0.000001").usec)
-    assert_equal(100000000, Time.at("0.1").nsec)
-    assert_equal(10000000, Time.at("0.01").nsec)
-    assert_equal(1000000, Time.at("0.001").nsec)
-    assert_equal(100000, Time.at("0.0001").nsec)
-    assert_equal(10000, Time.at("0.00001").nsec)
-    assert_equal(1000, Time.at("0.000001").nsec)
-    assert_equal(100, Time.at("0.0000001").nsec)
-    assert_equal(10, Time.at("0.00000001").nsec)
-    assert_equal(1, Time.at("0.000000001").nsec)
+    assert_equal(100000, Time.at("0.1".to_r).usec)
+    assert_equal(10000, Time.at("0.01".to_r).usec)
+    assert_equal(1000, Time.at("0.001".to_r).usec)
+    assert_equal(100, Time.at("0.0001".to_r).usec)
+    assert_equal(10, Time.at("0.00001".to_r).usec)
+    assert_equal(1, Time.at("0.000001".to_r).usec)
+    assert_equal(100000000, Time.at("0.1".to_r).nsec)
+    assert_equal(10000000, Time.at("0.01".to_r).nsec)
+    assert_equal(1000000, Time.at("0.001".to_r).nsec)
+    assert_equal(100000, Time.at("0.0001".to_r).nsec)
+    assert_equal(10000, Time.at("0.00001".to_r).nsec)
+    assert_equal(1000, Time.at("0.000001".to_r).nsec)
+    assert_equal(100, Time.at("0.0000001".to_r).nsec)
+    assert_equal(10, Time.at("0.00000001".to_r).nsec)
+    assert_equal(1, Time.at("0.000000001".to_r).nsec)
     assert_equal(100000, Time.at(0.1).usec)
     assert_equal(10000, Time.at(0.01).usec)
     assert_equal(1000, Time.at(0.001).usec)