diff --git a/klippy/extras/tuning_tower.py b/klippy/extras/tuning_tower.py
index 753e5433..87a0093d 100644
--- a/klippy/extras/tuning_tower.py
+++ b/klippy/extras/tuning_tower.py
@@ -13,6 +13,7 @@ class TuningTower:
         self.normal_transform = None
         self.last_position = [0., 0., 0., 0.]
         self.last_z = self.start = self.factor = self.band = 0.
+        self.last_command_value = None
         self.command_fmt = ""
         # Register command
         self.gcode = self.printer.lookup_object("gcode")
@@ -35,6 +36,7 @@ class TuningTower:
             self.command_fmt = "%s %s=%%.9f" % (command, parameter)
         self.normal_transform = self.gcode.set_move_transform(self, force=True)
         self.last_z = -99999999.9
+        self.last_command_value = None
         self.get_position()
         gcmd.respond_info("Starting tuning test (start=%.6f factor=%.6f)"
                           % (self.start, self.factor))
@@ -57,11 +59,11 @@ class TuningTower:
                 self.end_test()
             else:
                 # Process update
-                z_offset = self.gcode.get_status()['base_zpos']
-                oldval = self.calc_value(self.last_z - z_offset)
-                newval = self.calc_value(z - z_offset)
+                gcode_z = self.gcode.get_status()['gcode_position'].z
+                newval = self.calc_value(gcode_z)
                 self.last_z = z
-                if newval != oldval:
+                if newval != self.last_command_value:
+                    self.last_command_value = newval
                     self.gcode.run_script_from_command(self.command_fmt
                                                        % (newval,))
         # Forward move to actual handler
diff --git a/klippy/gcode.py b/klippy/gcode.py
index 579a7c64..8180e2e9 100644
--- a/klippy/gcode.py
+++ b/klippy/gcode.py
@@ -187,10 +187,6 @@ class GCodeParser:
             'last_ypos': self.last_position[1],
             'last_zpos': self.last_position[2],
             'last_epos': self.last_position[3],
-            'base_xpos': self.base_position[0],
-            'base_ypos': self.base_position[1],
-            'base_zpos': self.base_position[2],
-            'base_epos': self.base_position[3],
             'homing_origin': homing.Coord(*self.homing_position),
             'gcode_position': homing.Coord(*move_position),
         }