diff --git a/Marlin/src/gcode/calibrate/M48.cpp b/Marlin/src/gcode/calibrate/M48.cpp
index 766d3fb91..763b04184 100644
--- a/Marlin/src/gcode/calibrate/M48.cpp
+++ b/Marlin/src/gcode/calibrate/M48.cpp
@@ -40,7 +40,7 @@
  * M48: Z probe repeatability measurement function.
  *
  * Usage:
- *   M48 <P#> <X#> <Y#> <V#> <E> <L#>
+ *   M48 <P#> <X#> <Y#> <V#> <E> <L#> <S>
  *     P = Number of sampled points (4-50, default 10)
  *     X = Sample X position
  *     Y = Sample Y position
diff --git a/Marlin/src/gcode/gcode.h b/Marlin/src/gcode/gcode.h
index e97646f9c..bce0cf371 100644
--- a/Marlin/src/gcode/gcode.h
+++ b/Marlin/src/gcode/gcode.h
@@ -97,7 +97,7 @@
  * M34  - Set SD Card sorting options. (Requires SDCARD_SORT_ALPHA)
  * M42  - Change pin status via gcode: M42 P<pin> S<value>. LED pin assumed if P is omitted.
  * M43  - Display pin status, watch pins for changes, watch endstops & toggle LED, Z servo probe test, toggle pins
- * M48  - Measure Z Probe repeatability: M48 P<points> X<pos> Y<pos> V<level> E<engage> L<legs>. (Requires Z_MIN_PROBE_REPEATABILITY_TEST)
+ * M48  - Measure Z Probe repeatability: M48 P<points> X<pos> Y<pos> V<level> E<engage> L<legs> <S>chizoid. (Requires Z_MIN_PROBE_REPEATABILITY_TEST)
  * M75  - Start the print job timer.
  * M76  - Pause the print job timer.
  * M77  - Stop the print job timer.