diff --git a/python_src/lasp/lasp_measurement.py b/python_src/lasp/lasp_measurement.py
index f24fbea..da11083 100644
--- a/python_src/lasp/lasp_measurement.py
+++ b/python_src/lasp/lasp_measurement.py
@@ -91,6 +91,9 @@ class MeasurementType(Enum):
     # Measurement serves as impedance tube calibration (long tube case)
     muZCalLong = 1 << 3
 
+    # Series impedance reference
+    muZSeriesImpedanceRef = 1 << 4
+
     def __str__(self):
         match self:
             case MeasurementType.NotSpecific: return '-'
@@ -98,6 +101,7 @@ class MeasurementType(Enum):
             case MeasurementType.CALGeneral: return 'General calibration'
             case MeasurementType.muZCalShort: return 'ASCEE μZ short length calibration'
             case MeasurementType.muZCalLong: return 'ASCEE μZ long length calibration'
+            case MeasurementType.muZSeriesImpedanceRef: return 'ASCEE μZ series impedance empty reference'
             case _: raise ValueError("Not a MeasurementType")