diff --git a/Marlin/src/Marlin.cpp b/Marlin/src/Marlin.cpp
index 0de54efa78..f83935698f 100644
--- a/Marlin/src/Marlin.cpp
+++ b/Marlin/src/Marlin.cpp
@@ -215,10 +215,6 @@ static millis_t stepper_inactive_time = (DEFAULT_STEPPER_DEACTIVE_TIME) * 1000UL
   millis_t lastUpdateMillis;
 #endif
 
-#if ENABLED(CNC_WORKSPACE_PLANES)
-  static WorkspacePlane workspace_plane = PLANE_XY;
-#endif
-
 /**
  * ***************************************************************************
  * ******************************** FUNCTIONS ********************************
@@ -361,10 +357,6 @@ void suicide() {
  ***************** GCode Handlers *****************
  **************************************************/
 
-#if ENABLED(CNC_WORKSPACE_PLANES)
-  #include "gcode/geometry/G17-G19.h"
-#endif
-
 #if ENABLED(INCH_MODE_SUPPORT)
   #include "gcode/units/G20_G21.h"
 #endif
diff --git a/Marlin/src/core/enum.h b/Marlin/src/core/enum.h
index 9bf3ba856a..9170fd037b 100644
--- a/Marlin/src/core/enum.h
+++ b/Marlin/src/core/enum.h
@@ -148,12 +148,4 @@ enum LCDViewAction {
   };
 #endif
 
-/**
- * Workspace planes only apply to G2/G3 moves
- * (and "canned cycles" - not a current feature)
- */
-#if ENABLED(CNC_WORKSPACE_PLANES)
-  enum WorkspacePlane { PLANE_XY, PLANE_ZX, PLANE_YZ };
-#endif
-
 #endif // __ENUM_H__
diff --git a/Marlin/src/gcode/gcode.cpp b/Marlin/src/gcode/gcode.cpp
index 471152942b..1577defd35 100644
--- a/Marlin/src/gcode/gcode.cpp
+++ b/Marlin/src/gcode/gcode.cpp
@@ -48,6 +48,10 @@ bool GcodeSuite::axis_relative_modes[] = AXIS_RELATIVE_MODES;
   uint8_t GcodeSuite::host_keepalive_interval = DEFAULT_KEEPALIVE_INTERVAL;
 #endif
 
+#if ENABLED(CNC_WORKSPACE_PLANES)
+  GcodeSuite::WorkspacePlane GcodeSuite::workspace_plane = PLANE_XY;
+#endif
+
 /**
  * Set target_extruder from the T parameter or the active_extruder
  *
@@ -112,9 +116,6 @@ void GcodeSuite::dwell(millis_t time) {
 //
 // Placeholders for non-migrated codes
 //
-extern void gcode_G17();
-extern void gcode_G18();
-extern void gcode_G19();
 extern void gcode_G20();
 extern void gcode_G21();
 extern void gcode_G27();
@@ -318,13 +319,13 @@ void GcodeSuite::process_next_command() {
 
       #if ENABLED(CNC_WORKSPACE_PLANES)
         case 17: // G17: Select Plane XY
-          gcode_G17();
+          G17();
           break;
         case 18: // G18: Select Plane ZX
-          gcode_G18();
+          G18();
           break;
         case 19: // G19: Select Plane YZ
-          gcode_G19();
+          G19();
           break;
       #endif // CNC_WORKSPACE_PLANES
 
diff --git a/Marlin/src/gcode/gcode.h b/Marlin/src/gcode/gcode.h
index eb77b7b553..90c1aabb6e 100644
--- a/Marlin/src/gcode/gcode.h
+++ b/Marlin/src/gcode/gcode.h
@@ -256,6 +256,15 @@ public:
 
   static bool axis_relative_modes[];
 
+  #if ENABLED(CNC_WORKSPACE_PLANES)
+    /**
+     * Workspace planes only apply to G2/G3 moves
+     * (and "canned cycles" - not a current feature)
+     */
+    enum WorkspacePlane { PLANE_XY, PLANE_ZX, PLANE_YZ };
+    static WorkspacePlane workspace_plane;
+  #endif
+
   static millis_t previous_cmd_ms;
   FORCE_INLINE static void refresh_cmd_timeout() { previous_cmd_ms = millis(); }
 
diff --git a/Marlin/src/gcode/geometry/G17-G19.h b/Marlin/src/gcode/geometry/G17-G19.cpp
similarity index 58%
rename from Marlin/src/gcode/geometry/G17-G19.h
rename to Marlin/src/gcode/geometry/G17-G19.cpp
index 7bff34fe40..d386e2eed2 100644
--- a/Marlin/src/gcode/geometry/G17-G19.h
+++ b/Marlin/src/gcode/geometry/G17-G19.cpp
@@ -20,10 +20,25 @@
  *
  */
 
-void report_workspace_plane() {
+#include "../../inc/MarlinConfig.h"
+
+#if ENABLED(CNC_WORKSPACE_PLANES)
+
+#include "../gcode.h"
+
+inline void report_workspace_plane() {
   SERIAL_ECHO_START();
   SERIAL_ECHOPGM("Workspace Plane ");
-  serialprintPGM(workspace_plane == PLANE_YZ ? PSTR("YZ\n") : workspace_plane == PLANE_ZX ? PSTR("ZX\n") : PSTR("XY\n"));
+  serialprintPGM(
+      gcode.workspace_plane == GcodeSuite::PLANE_YZ ? PSTR("YZ\n")
+    : gcode.workspace_plane == GcodeSuite::PLANE_ZX ? PSTR("ZX\n")
+                                                    : PSTR("XY\n")
+  );
+}
+
+inline void set_workspace_plane(const GcodeSuite::WorkspacePlane plane) {
+  gcode.workspace_plane = plane;
+  if (DEBUGGING(INFO)) report_workspace_plane();
 }
 
 /**
@@ -31,6 +46,8 @@ void report_workspace_plane() {
  * G18: Select Plane ZX
  * G19: Select Plane YZ
  */
-void gcode_G17() { workspace_plane = PLANE_XY; }
-void gcode_G18() { workspace_plane = PLANE_ZX; }
-void gcode_G19() { workspace_plane = PLANE_YZ; }
+void GcodeSuite::G17() { set_workspace_plane(PLANE_XY); }
+void GcodeSuite::G18() { set_workspace_plane(PLANE_ZX); }
+void GcodeSuite::G19() { set_workspace_plane(PLANE_YZ); }
+
+#endif // CNC_WORKSPACE_PLANES
diff --git a/Marlin/src/gcode/motion/G2_G3.cpp b/Marlin/src/gcode/motion/G2_G3.cpp
index 2986a86a65..44f0f53ba7 100644
--- a/Marlin/src/gcode/motion/G2_G3.cpp
+++ b/Marlin/src/gcode/motion/G2_G3.cpp
@@ -50,10 +50,10 @@ void plan_arc(
 ) {
   #if ENABLED(CNC_WORKSPACE_PLANES)
     AxisEnum p_axis, q_axis, l_axis;
-    switch (workspace_plane) {
-      case PLANE_XY: p_axis = X_AXIS; q_axis = Y_AXIS; l_axis = Z_AXIS; break;
-      case PLANE_ZX: p_axis = Z_AXIS; q_axis = X_AXIS; l_axis = Y_AXIS; break;
-      case PLANE_YZ: p_axis = Y_AXIS; q_axis = Z_AXIS; l_axis = X_AXIS; break;
+    switch (gcode.workspace_plane) {
+      case GcodeSuite::PLANE_XY: p_axis = X_AXIS; q_axis = Y_AXIS; l_axis = Z_AXIS; break;
+      case GcodeSuite::PLANE_ZX: p_axis = Z_AXIS; q_axis = X_AXIS; l_axis = Y_AXIS; break;
+      case GcodeSuite::PLANE_YZ: p_axis = Y_AXIS; q_axis = Z_AXIS; l_axis = X_AXIS; break;
     }
   #else
     constexpr AxisEnum p_axis = X_AXIS, q_axis = Y_AXIS, l_axis = Z_AXIS;