diff --git a/lasp/lasp_measurement.py b/lasp/lasp_measurement.py
index 94120ee..be65350 100644
--- a/lasp/lasp_measurement.py
+++ b/lasp/lasp_measurement.py
@@ -247,7 +247,7 @@ class Measurement:
                 # If quantity data is not available, this is an 'old'
                 # measurement file.
                 logging.debug(f'Physical quantity data not available in measurement file. Assuming {SIQtys.default}')
-                self._qtys = [SIQtys.default for i in range(self.nchannels)]
+                self._qtys = [SIQtys.default() for i in range(self.nchannels)]
 
     def setAttribute(self, atrname, value):
         """