diff --git a/lisainstrument/instrument.py b/lisainstrument/instrument.py
index 1f682eb551c55ea89e01ef5a04f191f170e9c059..990ba7565ceb203d9b4b085f943fd3ae6ac6528b 100644
--- a/lisainstrument/instrument.py
+++ b/lisainstrument/instrument.py
@@ -319,7 +319,7 @@ class Instrument:
             logger.info("Interpolating gravitational-wave responses from GW file '%s'", self.gw_file)
             gwf = h5py.File(self.gw_file, 'r')
             self.gws = ForEachMOSA(lambda mosa: scipy.interpolate.InterpolatedUnivariateSpline(
-                gwf['t'][:], gwf[f'l_{mosa}'][:], k=5, ext='raise')(self.physics_t)
+                gwf['t'][:], gwf[f'l_{mosa}'][:], k=5, ext='zeros')(self.physics_t)
             )
             gwf.close()
         elif gws is None: