diff --git a/src/lava/lib/dl/slayer/spike/spike.py b/src/lava/lib/dl/slayer/spike/spike.py
index 4b2347d07..fe968ddb7 100644
--- a/src/lava/lib/dl/slayer/spike/spike.py
+++ b/src/lava/lib/dl/slayer/spike/spike.py
@@ -19,7 +19,7 @@ def _spike_backward(
         )
 
     return scale_rho * torch.exp(
-        -torch.clamp(voltage - threshold, max=0) / tau_rho
+        torch.clamp(voltage - threshold, max=0) / tau_rho
     )