diff --git a/icefall/checkpoint.py b/icefall/checkpoint.py
index ea50b32a9..c83c56a53 100644
--- a/icefall/checkpoint.py
+++ b/icefall/checkpoint.py
@@ -76,7 +76,7 @@ def save_checkpoint(
 
     if isinstance(model, DDP):
         model = model.module
-    
+
     checkpoint = {
         "model": model.state_dict(),
         "optimizer": optimizer.state_dict() if optimizer is not None else None,