diff --git a/Lib/test/test_weakref.py b/Lib/test/test_weakref.py
index ffa28a6..ecf1976 100644
--- a/Lib/test/test_weakref.py
+++ b/Lib/test/test_weakref.py
@@ -183,6 +183,17 @@
         self.assertEqual(L3[:5], p3[:5])
         self.assertEqual(L3[2:5], p3[2:5])
 
+    def test_proxy_unicode(self):
+        # See bug 5037
+        class C(object):
+            def __str__(self):
+                return "string"
+            def __bytes__(self):
+                return b"bytes"
+        instance = C()
+        self.assertTrue("__bytes__" in dir(weakref.proxy(instance)))
+        self.assertEqual(bytes(weakref.proxy(instance)), b"bytes")
+
     def test_proxy_index(self):
         class C:
             def __index__(self):