diff --git a/spanet/network/jet_reconstruction/jet_reconstruction_training.py b/spanet/network/jet_reconstruction/jet_reconstruction_training.py
index b5d6ea5..bc12d6c 100644
--- a/spanet/network/jet_reconstruction/jet_reconstruction_training.py
+++ b/spanet/network/jet_reconstruction/jet_reconstruction_training.py
@@ -238,7 +238,7 @@ def training_step(self, batch: Batch, batch_nb: int) -> Dict[str, Tensor]:
 
         # Take the weighted average of the symmetric loss terms.
         masks = masks.unsqueeze(1)
-        symmetric_losses = (weights * symmetric_losses).sum(-1) / masks.sum(-1)
+        symmetric_losses = (weights * symmetric_losses).sum(-1) / torch.clamp(masks.sum(-1), 1, None)
         assignment_loss, detection_loss = torch.unbind(symmetric_losses, 1)
 
         # ===================================================================================================