diff --git a/Marlin/G26_Mesh_Validation_Tool.cpp b/Marlin/G26_Mesh_Validation_Tool.cpp
index 58750934f..e8e03c4c5 100644
--- a/Marlin/G26_Mesh_Validation_Tool.cpp
+++ b/Marlin/G26_Mesh_Validation_Tool.cpp
@@ -773,7 +773,7 @@
 
         #if ENABLED(ARC_SUPPORT)
 
-          #define ARC_LENGTH(quarters)  (INTERSECTION_CIRCLE_RADIUS * PI * (quarters) / 2)
+          #define ARC_LENGTH(quarters)  (INTERSECTION_CIRCLE_RADIUS * M_PI * (quarters) / 2)
           float sx = circle_x + INTERSECTION_CIRCLE_RADIUS,   // default to full circle
                 ex = circle_x + INTERSECTION_CIRCLE_RADIUS,
                 sy = circle_y, ey = circle_y,