diff --git a/nc_time_axis/__init__.py b/nc_time_axis/__init__.py
index a5276ad..e37bcef 100644
--- a/nc_time_axis/__init__.py
+++ b/nc_time_axis/__init__.py
@@ -454,7 +454,7 @@ def has_year_zero(year):
         return cftime.date2num(ticks, self.date_unit, calendar=self.calendar)
 
 
-class NetCDFTimeConverter(mdates.DateConverter):
+class NetCDFTimeConverter(munits.ConversionInterface):
     """
     Converter for :py:class:`cftime.datetime` data.