diff --git a/Lib/test/test_hashlib.py b/Lib/test/test_hashlib.py
index d1b04128bf6df3..0c1680cfbce36b 100644
--- a/Lib/test/test_hashlib.py
+++ b/Lib/test/test_hashlib.py
@@ -253,6 +253,7 @@ def test_unknown_hash(self):
     def test_new_upper_to_lower(self):
         self.assertEqual(hashlib.new("SHA256").name, "sha256")
 
+    @support.thread_unsafe("modifies sys.modules")
     def test_get_builtin_constructor(self):
         get_builtin_constructor = getattr(hashlib,
                                           '__get_builtin_constructor')