diff --git a/src/engine.py b/src/engine.py
index 18775e1..809f3be 100644
--- a/src/engine.py
+++ b/src/engine.py
@@ -84,12 +84,15 @@ def parallel_fir(
             z_pre = fir_fn(
                 u,
                 weight,
-                bias,
+                bias=None,  # don't pass it here, add manually instead!  source of small error
                 stride=1,
                 padding=fir_length - 1,
                 groups=u.shape[1],
             )[..., :L]
 
+            # add manually instead!  source of small error
+            z_pre = z_pre + bias[None, :, None]
+
         # handle padding post fir, the only place with biases
         if type(padding_mask) == torch.Tensor:
             z_pre = z_pre * padding_mask[:, None]
@@ -289,9 +292,9 @@ def prefill_via_direct_recurrence(
         # x1v_: b, d, l, sdim, reim
         for i in range(L):
             state[..., 0] = poles[..., 0] * state[..., 0] - poles[..., 1] * state[..., 1] + x1v_[:, :, i, :, 0]
-            state[..., 1] = poles[..., 0] * state[..., 1] + poles[..., 1] * state[..., 0] + x1v_[:, :, i, :, 1] 
+            state[..., 1] = poles[..., 0] * state[..., 1] + poles[..., 1] * state[..., 0] + x1v_[:, :, i, :, 1]
             output[:, :, i] = torch.sum(residues * state, dim=-2)[..., 0]  # .real
-            
+
         inference_params.state_dict[self.layer_idx] = torch.view_as_complex(state.to(dtype=torch.float32))
 
         return output