diff --git a/dice_loss.py b/dice_loss.py
index fa2e987..631638f 100644
--- a/dice_loss.py
+++ b/dice_loss.py
@@ -20,7 +20,7 @@ class DiceCoeff(Function):
         grad_input = grad_target = None
 
         if self.needs_input_grad[0]:
-            grad_input = grad_output * 2 * (target * self.union + self.inter) \
+            grad_input = grad_output * 2 * (target * self.union - self.inter) \
                          / self.union * self.union
         if self.needs_input_grad[1]:
             grad_target = None