diff --git a/utils/loss.py b/utils/loss.py
index 31386328..12ec230a 100644
--- a/utils/loss.py
+++ b/utils/loss.py
@@ -775,12 +775,20 @@ class ComputeLossOTA:
                 matching_anchs[i].append(all_anch[layer_idx])
 
         for i in range(nl):
-            matching_bs[i] = torch.cat(matching_bs[i], dim=0)
-            matching_as[i] = torch.cat(matching_as[i], dim=0)
-            matching_gjs[i] = torch.cat(matching_gjs[i], dim=0)
-            matching_gis[i] = torch.cat(matching_gis[i], dim=0)
-            matching_targets[i] = torch.cat(matching_targets[i], dim=0)
-            matching_anchs[i] = torch.cat(matching_anchs[i], dim=0)
+            if matching_gis[i] != []:
+                matching_bs[i] = torch.cat(matching_bs[i], dim=0)
+                matching_as[i] = torch.cat(matching_as[i], dim=0)
+                matching_gjs[i] = torch.cat(matching_gjs[i], dim=0)
+                matching_gis[i] = torch.cat(matching_gis[i], dim=0)
+                matching_targets[i] = torch.cat(matching_targets[i], dim=0)
+                matching_anchs[i] = torch.cat(matching_anchs[i], dim=0)
+            else:
+                matching_bs[i] = torch.tensor([], device='cuda:0', dtype=torch.int64)
+                matching_as[i] = torch.tensor([], device='cuda:0', dtype=torch.int64)
+                matching_gjs[i] = torch.tensor([], device='cuda:0', dtype=torch.int64)
+                matching_gis[i] = torch.tensor([], device='cuda:0', dtype=torch.int64)
+                matching_targets[i] = torch.tensor([], device='cuda:0', dtype=torch.int64)
+                matching_anchs[i] = torch.tensor([], device='cuda:0', dtype=torch.int64)
 
         return matching_bs, matching_as, matching_gjs, matching_gis, matching_targets, matching_anchs