diff --git a/sdk/python/kfp/components/_data_passing.py b/sdk/python/kfp/components/_data_passing.py
index 9fcad5ba2e1..da89ae321c3 100644
--- a/sdk/python/kfp/components/_data_passing.py
+++ b/sdk/python/kfp/components/_data_passing.py
@@ -45,6 +45,8 @@ def _deserialize_bool(s) -> bool:
 
 
 def _serialize_json(obj) -> str:
+    if isinstance(obj, str):
+        return obj
     import json
     def default_serializer(obj):
         if hasattr(obj, 'to_struct'):
@@ -55,6 +57,8 @@ def default_serializer(obj):
 
 
 def _serialize_base64_pickle(obj) -> str:
+    if isinstance(obj, str):
+        return obj
     import base64
     import pickle
     return base64.b64encode(pickle.dumps(obj)).decode('ascii')