diff --git a/klippy/extras/tmc.py b/klippy/extras/tmc.py
index acc0b607..7b9280dd 100644
--- a/klippy/extras/tmc.py
+++ b/klippy/extras/tmc.py
@@ -287,7 +287,7 @@ def TMCStealthchopHelper(config, mcu_tmc, tmc_freq):
     if velocity:
         stepper_name = " ".join(config.get_name().split()[1:])
         stepper_config = config.getsection(stepper_name)
-        step_dist = stepper_config.getfloat('step_distance')
+        step_dist = stepper_config.getfloat('step_distance', note_valid=False)
         step_dist_256 = step_dist / (1 << fields.get_field("MRES"))
         threshold = int(tmc_freq * step_dist_256 / velocity + .5)
         fields.set_field("TPWMTHRS", max(0, min(0xfffff, threshold)))