diff --git a/MAVProxy/modules/mavproxy_param.py b/MAVProxy/modules/mavproxy_param.py
index 5b8879eb40..74152bc1e8 100644
--- a/MAVProxy/modules/mavproxy_param.py
+++ b/MAVProxy/modules/mavproxy_param.py
@@ -645,7 +645,7 @@ def param_bitmask_modify(self, master, args):
             return
 
         # Update the parameter
-        self.set_parameter(master, uname, value, attempts=3, parm_type=ptype)
+        self.set_parameter(master, uname, value, attempts=3, param_type=ptype)
 
     def set_parameter(self, master, name, value, attempts=None, param_type=None):
         '''convenient intermediate method which determines parameter type for