diff --git a/python/ppml/src/bigdl/ppml/fl/nn/nn_service.py b/python/ppml/src/bigdl/ppml/fl/nn/nn_service.py
index 5f9a45dabec..e8387846a53 100644
--- a/python/ppml/src/bigdl/ppml/fl/nn/nn_service.py
+++ b/python/ppml/src/bigdl/ppml/fl/nn/nn_service.py
@@ -42,7 +42,7 @@ def __init__(self, conf, **kargs) -> None:
             'pt': pt_agg.Aggregator(conf, **kargs)}
         self.model_dir = tempfile.mkdtemp() # store tmp file dir
         self.model_path = os.path.join(self.model_dir, "vfl_server_model")
-	self.client_num = int(self.client_num)
+        self.client_num = int(self.client_num)
         self.condition = Condition()
         self._lock = threading.Lock()
 
diff --git a/python/ppml/src/bigdl/ppml/fl/nn/pytorch/aggregator.py b/python/ppml/src/bigdl/ppml/fl/nn/pytorch/aggregator.py
index d5b79ec4dae..34c4575262b 100644
--- a/python/ppml/src/bigdl/ppml/fl/nn/pytorch/aggregator.py
+++ b/python/ppml/src/bigdl/ppml/fl/nn/pytorch/aggregator.py
@@ -31,7 +31,7 @@ def __init__(self, conf) -> None:
         self.client_data = {'train':{}, 'eval':{}, 'pred':{}}
         self.server_data = {'train':{}, 'eval':{}, 'pred':{}}
         self.client_num = conf['clientNum']
-	self.client_num = int(self.client_num)
+        self.client_num = int(self.client_num)
         self.condition = Condition()
         self._lock = threading.Lock()
         self.optimizer_cls = None