diff --git a/api/i_step_motor_ctrl_module.hpp b/api/i_step_motor_ctrl_module.hpp
index 22e4c1b..2d39a86 100644
--- a/api/i_step_motor_ctrl_module.hpp
+++ b/api/i_step_motor_ctrl_module.hpp
@@ -43,7 +43,8 @@ class I_StepMotorCtrlModule {
 
   typedef struct {
     s32 x_shaft;
-    s32 distance_scale;  // 0.001
+    s32 distance_scale;              //
+    s32 distance_scale_denominator;  //
     s32 ihold;
     s32 irun;
     u16 iholddelay;
@@ -59,7 +60,7 @@ class I_StepMotorCtrlModule {
     s32 run_to_zero_max_d;
     s32 run_to_zero_speed;
     s32 run_to_zero_dec;
-    
+
     s32 look_zero_edge_max_d;
     s32 look_zero_edge_speed;
     s32 look_zero_edge_dec;