diff --git a/icefall/checkpoint.py b/icefall/checkpoint.py
index c83c56a53..d09c72328 100644
--- a/icefall/checkpoint.py
+++ b/icefall/checkpoint.py
@@ -444,6 +444,11 @@ def average_checkpoints_with_averaged_model(
         scaling_factor=weight_end,
     )
 
+    # avoid negative running variance of batchnorm layers
+    for k in avg.keys():
+        if k.split('.')[-1] == 'running_var':
+            avg[k] = torch.clip(avg[k], min=1e-2)    
+    
     return avg