diff --git a/compliance_checker/cfutil.py b/compliance_checker/cfutil.py
index 8bcce331..22336140 100644
--- a/compliance_checker/cfutil.py
+++ b/compliance_checker/cfutil.py
@@ -2028,7 +2028,7 @@ def guess_feature_type(nc, variable):
         return "reduced-grid"
 
 
-def units_convertible(units1, units2, reftimeistime=True):
+def units_convertible(units1, units2):
     """
     Return True if a Unit representing the string units1 can be converted
     to a Unit representing the string units2, else False.