diff --git a/src/geophires_x/Economics.py b/src/geophires_x/Economics.py
index 6590535e..316125f2 100644
--- a/src/geophires_x/Economics.py
+++ b/src/geophires_x/Economics.py
@@ -1383,7 +1383,7 @@ def __init__(self, model: Model):
         )
 
         fir_default_unit = PercentUnit.PERCENT
-        fir_default_val = self.discountrate.quantity().to(fir_default_unit.value).magnitude
+        fir_default_val = self.discountrate.quantity().to('percent').magnitude  # pint can't handle '%' in python 3.8
         self.FixedInternalRate = self.ParameterDict[self.FixedInternalRate.Name] = floatParameter(
             "Fixed Internal Rate",
             DefaultValue=fir_default_val,