diff --git a/python/examples/pipeline/imdb_model_ensemble/test_pipeline_server.py b/python/examples/pipeline/imdb_model_ensemble/test_pipeline_server.py
index 08c6ccce45f0ef707d6921955b487b324c45b03b..0258701b019ae1e60a313073ffbc8342917f0fd8 100644
--- a/python/examples/pipeline/imdb_model_ensemble/test_pipeline_server.py
+++ b/python/examples/pipeline/imdb_model_ensemble/test_pipeline_server.py
@@ -46,7 +46,7 @@ class ImdbRequestOp(RequestOp):
 
 
 class CombineOp(Op):
-    def preprocess(self, input_data, private_obj):
+    def preprocess(self, input_data):
         combined_prediction = 0
         for op_name, data in input_data.items():
             _LOGGER.info("{}: {}".format(op_name, data["prediction"]))