diff --git a/swash/config-nb.ini b/swash/config-nb.ini
index 67aa1b5..49b0397 100644
--- a/swash/config-nb.ini
+++ b/swash/config-nb.ini
@@ -11,5 +11,5 @@ mpi=8
 inp=inp_post/real_spec_interp_nb
 #compare=
 out=out_post/real_spec_interp_nb
-x0=-1250
+x0=-250
 t0=180
diff --git a/swash/processing/read_mat.py b/swash/processing/read_mat.py
index 9180c2d..24fce99 100644
--- a/swash/processing/read_mat.py
+++ b/swash/processing/read_mat.py
@@ -72,9 +72,9 @@ class ReadSwash:
             [
                 raw[i0][0]
                 for i0 in np.char.add(
-                    np.char.replace(f"{var_name}[]_", "[]", np.arange(*ra).astype("U1"))[
-                        None, :
-                    ],
+                    np.char.replace(
+                        f"{var_name}[]_", "[]", np.arange(*ra).astype("U1")
+                    )[None, :],
                     self._i[:, None],
                 ).reshape(-1)
             ],