diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index cd310ea..81d1671 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -505,9 +505,11 @@
             self.assertEqual(len(os.urandom(100)), 100)
             self.assertEqual(len(os.urandom(1000)), 1000)
             # see http://bugs.python.org/issue3708
-            self.assertEqual(len(os.urandom(0.9)), 0)
-            self.assertEqual(len(os.urandom(1.1)), 1)
-            self.assertEqual(len(os.urandom(2.0)), 2)
+            with test_support.check_warnings():
+                # silence deprecation warnings about float arguments
+                self.assertEqual(len(os.urandom(0.9)), 0)
+                self.assertEqual(len(os.urandom(1.1)), 1)
+                self.assertEqual(len(os.urandom(2.0)), 2)
         except NotImplementedError:
             pass