diff --git a/Lib/pstats.py b/Lib/pstats.py
index e781b91..0f93ae0 100644
--- a/Lib/pstats.py
+++ b/Lib/pstats.py
@@ -45,9 +45,9 @@
     TIME = 'time', 'tottime'
 
     def __new__(cls, *values):
-        obj = str.__new__(cls)
-
-        obj._value_ = values[0]
+        value = values[0]
+        obj = str.__new__(cls, value)
+        obj._value_ = value
         for other_value in values[1:]:
             cls._value2member_map_[other_value] = obj
         obj._all_values = values
diff --git a/Lib/test/test_pstats.py b/Lib/test/test_pstats.py
index 10559de..4f78b99 100644
--- a/Lib/test/test_pstats.py
+++ b/Lib/test/test_pstats.py
@@ -95,5 +95,9 @@
         self.assertIn('pass2', funcs_called)
         self.assertIn('pass3', funcs_called)
 
+    def test_SortKey_enum(self):
+        self.assertEqual(SortKey.FILENAME, 'filename')
+        self.assertNotEqual(SortKey.FILENAME, SortKey.CALLS)
+
 if __name__ == "__main__":
     unittest.main()