diff --git a/Marlin/src/gcode/calibrate/G33.cpp b/Marlin/src/gcode/calibrate/G33.cpp
index a3cb7f0b9d..7530737dde 100644
--- a/Marlin/src/gcode/calibrate/G33.cpp
+++ b/Marlin/src/gcode/calibrate/G33.cpp
@@ -649,7 +649,7 @@ void GcodeSuite::G33() {
         SERIAL_ECHOLNPGM("Save with M500 and/or copy to Configuration.h");
       }
       else { // !end iterations
-        SString<14> msg;
+        SString<15> msg;
         if (iterations < 31)
           msg.setf(F("Iteration : %02i"), (unsigned int)iterations);
         else