diff --git a/cnsproject/network/neural_populations.py b/cnsproject/network/neural_populations.py
index b52713f..7356a4b 100644
--- a/cnsproject/network/neural_populations.py
+++ b/cnsproject/network/neural_populations.py
@@ -63,7 +63,7 @@ def __init__(
             if self.additive_spike_trace:
                 self.register_buffer("trace_scale", torch.tensor(trace_scale))
 
-            self.register_buffer("trace_decay", torch.empty_like(tau_s))
+            self.register_buffer("trace_decay", torch.empty_like(self.tau_s))
 
         self.is_inhibitory = is_inhibitory
         self.learning = learning