diff --git a/s3tests/functional/test_s3.py b/s3tests/functional/test_s3.py
index ed87400..576a7af 100644
--- a/s3tests/functional/test_s3.py
+++ b/s3tests/functional/test_s3.py
@@ -6808,6 +6808,8 @@ def test_versioning_obj_plain_null_version_overwrite():
     key.set_contents_from_string(content2)
 
     eq(key.get_contents_as_string(), content2)
+    # get_contents_to_string() will set key.version_id, clear it
+    key.version_id = None
 
     version_id = None
     for k in bucket.list_versions():