diff --git a/pychron/spectrometer/isotopx/magnet/ngx.py b/pychron/spectrometer/isotopx/magnet/ngx.py
index 9910425ac..f5cde79dd 100644
--- a/pychron/spectrometer/isotopx/magnet/ngx.py
+++ b/pychron/spectrometer/isotopx/magnet/ngx.py
@@ -33,7 +33,7 @@ def read_mass(self):
         self.microcontroller.triggered = False
         return self.ask("GETMASS")
 
-    def set_mass(self, v, delay=None, deflect=False):
+    def set_mass(self, v, delay=None, deflect=False, **kw):
         """
 
         :param v: mass