diff --git a/src/lasp/lasp_measurement.py b/src/lasp/lasp_measurement.py
index 899bb74..3aeeb27 100644
--- a/src/lasp/lasp_measurement.py
+++ b/src/lasp/lasp_measurement.py
@@ -834,7 +834,6 @@ class Measurement:
             if len(qtys) != nchannels:
                 raise RuntimeError("Illegal length of qtys list given")
 
-        qtyvals = [qty.value for qty in qtys]
 
         with h5.File(mfn, 'w') as hf:
             hf.attrs['samplerate'] = samplerate
@@ -844,7 +843,7 @@ class Measurement:
             hf.attrs['nchannels'] = nchannels
 
             # Add physical quantity indices
-            hf.attrs['qtys_enum_idx'] = [qtyval.toInt() for qtyval in qtyvals]
+            hf.attrs['qtys_enum_idx'] = [qty.toInt() for qty in qtys]
 
             # Add channel names in case given
             if channelNames is not None: