diff --git a/misc/finiterectlat-constant-driving.py b/misc/finiterectlat-constant-driving.py
index 4bf2cb9..bf742bc 100755
--- a/misc/finiterectlat-constant-driving.py
+++ b/misc/finiterectlat-constant-driving.py
@@ -254,7 +254,7 @@ outfile = defaultprefix + ".npz" if a.output is None else a.output
 np.savez(outfile, meta={**vars(a), 'qpms_version' : qpms.__version__()}, 
 		 omega=omega, wavenumber=wavenumber, nelem=nelem, wavevector=np.array(a.wavevector), phases=phases, 
                  positions = ss.positions[:,:2],
-                 scattered_ir_packed = scattered_ir, 
+                 scattered_ir_packed = np.array(scattered_ir, dtype=np.object),
                  scattered_full = scattered_full,
                  ir_contained = ir_contained,
                  t=t, l=l, m=m,