diff --git a/fcos_core/layers/sigmoid_focal_loss.py b/fcos_core/layers/sigmoid_focal_loss.py
index 3fe9bc2b..099cf9ff 100644
--- a/fcos_core/layers/sigmoid_focal_loss.py
+++ b/fcos_core/layers/sigmoid_focal_loss.py
@@ -49,7 +49,8 @@ def sigmoid_focal_loss_cpu(logits, targets, gamma, alpha):
     p = torch.sigmoid(logits)
     term1 = (1 - p) ** gamma * torch.log(p)
     term2 = p ** gamma * torch.log(1 - p)
-    return -(t == class_range).float() * term1 * alpha - ((t != class_range) * (t >= 0)).float() * term2 * (1 - alpha)
+#     return -(t == class_range).float() * term1 * alpha - ((t != class_range) * (t >= 0)).float() * term2 * (1 - alpha)
+    return -(t == class_range).float() * term1 * alpha - ((t >= 0) & (t != class_range)).float() * term2 * (1 - alpha)
 
 
 class SigmoidFocalLoss(nn.Module):