diff --git a/bilby/gw/waveform_generator.py b/bilby/gw/waveform_generator.py
index 687bcbc996d59c3f55aac0bebdac070a0599fdba..5642a9937b6199c6db77172dc390ae3f94fa58eb 100644
--- a/bilby/gw/waveform_generator.py
+++ b/bilby/gw/waveform_generator.py
@@ -77,7 +77,7 @@ class WaveformGenerator(object):
             tdsm_name = self.time_domain_source_model.__name__
         else:
             tdsm_name = None
-        if self.parameter_conversion.__name__ == '<lambda>':
+        if self.parameter_conversion.__name__ == '_default_parameter_conversion':
             param_conv_name = None
         else:
             param_conv_name = self.parameter_conversion.__name__