diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 261599401..81bbea097 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -13,7 +13,7 @@ jobs:
     strategy:
       matrix:
         os: [windows-latest, ubuntu-16.04, ubuntu-18.04, macos-latest]
-        python-version: [3.6, 3.7, 3.8]
+        python-version: [3.7, 3.8]
 
     steps:
     - uses: actions/checkout@v2
diff --git a/qlib/workflow/record_temp.py b/qlib/workflow/record_temp.py
index 6381b914e..a617f5d1f 100644
--- a/qlib/workflow/record_temp.py
+++ b/qlib/workflow/record_temp.py
@@ -148,7 +148,7 @@ class SignalRecord(RecordTemp):
                 raw_label = self.dataset.prepare(**params)
 
             self.recorder.save_objects(**{"label.pkl": raw_label})
-            self.dataset.__class__ =  orig_cls
+            self.dataset.__class__ = orig_cls
 
     def list(self):
         return ["pred.pkl", "label.pkl"]