diff --git a/python_src/lasp/lasp_measurement.py b/python_src/lasp/lasp_measurement.py
index 6b70fd3..f415a02 100644
--- a/python_src/lasp/lasp_measurement.py
+++ b/python_src/lasp/lasp_measurement.py
@@ -1111,7 +1111,6 @@ 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
@@ -1121,7 +1120,7 @@ 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: