diff --git a/src/tuesday/core/instrument_models/noise.py b/src/tuesday/core/instrument_models/noise.py
index aae4696d..6ce5140d 100644
--- a/src/tuesday/core/instrument_models/noise.py
+++ b/src/tuesday/core/instrument_models/noise.py
@@ -415,12 +415,7 @@ def filter_chunk(uv_chunk, freqs_chunk):
 
         uvtau = np.fft.fft(uv_chunk, axis=-1)
         this_dnu = np.mean(np.diff(freqs_chunk))
-        tau = (
-            np.fft.fftshift(
-                np.fft.fftfreq(uv_chunk.shape[-1], d=this_dnu.to(un.Hz).value)
-            )
-            * un.s
-        )
+        tau = np.fft.fftfreq(uv_chunk.shape[-1], d=this_dnu.to(un.Hz).value) * un.s
 
         kperp_mag = np.add.outer(kperp_grid**2, kperp_grid**2) ** 0.5
         umag = kperp_mag / dk_du(f2z(f0), with_h=with_h)
@@ -429,7 +424,7 @@ def filter_chunk(uv_chunk, freqs_chunk):
         # frequencies are probably not exactly regular).
         wedge = wedge_slope * umag / f0
 
-        mask = tau[None, None] < wedge[:, :, None] + buffer
+        mask = np.abs(tau)[None, None] < wedge[:, :, None] + buffer
         uvtau[:, mask] = 0.0
         return np.fft.ifft(uvtau, axis=-1)