diff --git a/Marlin/src/Marlin.cpp b/Marlin/src/Marlin.cpp
index 8798e824b0..464b552dc5 100644
--- a/Marlin/src/Marlin.cpp
+++ b/Marlin/src/Marlin.cpp
@@ -352,10 +352,6 @@ bool pin_is_protected(const int8_t pin) {
   return false;
 }
 
-#if ENABLED(PIDTEMPBED)
-  #include "gcode/config/M304.h"
-#endif
-
 #if defined(CHDK) || HAS_PHOTOGRAPH
   #include "gcode/feature/camera/M240.h"
 #endif
diff --git a/Marlin/src/gcode/config/M304.h b/Marlin/src/gcode/config/M304.cpp
similarity index 88%
rename from Marlin/src/gcode/config/M304.h
rename to Marlin/src/gcode/config/M304.cpp
index c460f1648d..a27adfc64a 100644
--- a/Marlin/src/gcode/config/M304.h
+++ b/Marlin/src/gcode/config/M304.cpp
@@ -20,7 +20,14 @@
  *
  */
 
-void gcode_M304() {
+#include "../../inc/MarlinConfig.h"
+
+#if ENABLED(PIDTEMPBED)
+
+#include "../gcode.h"
+#include "../../module/temperature.h"
+
+void GcodeSuite::M304() {
   if (parser.seen('P')) thermalManager.bedKp = parser.value_float();
   if (parser.seen('I')) thermalManager.bedKi = scalePID_i(parser.value_float());
   if (parser.seen('D')) thermalManager.bedKd = scalePID_d(parser.value_float());
@@ -32,3 +39,5 @@ void gcode_M304() {
   SERIAL_ECHOPAIR(" i:", unscalePID_i(thermalManager.bedKi));
   SERIAL_ECHOLNPAIR(" d:", unscalePID_d(thermalManager.bedKd));
 }
+
+#endif // PIDTEMPBED
diff --git a/Marlin/src/gcode/gcode.cpp b/Marlin/src/gcode/gcode.cpp
index 9a24eb877d..5f965ddb50 100644
--- a/Marlin/src/gcode/gcode.cpp
+++ b/Marlin/src/gcode/gcode.cpp
@@ -122,7 +122,6 @@ extern void gcode_M165();
 extern void gcode_M240();
 extern void gcode_M250();
 extern void gcode_M302();
-extern void gcode_M304();
 extern void gcode_M350();
 extern void gcode_M351();
 extern void gcode_M355();
@@ -573,10 +572,8 @@ void GcodeSuite::process_next_command() {
       #endif
 
       #if ENABLED(PIDTEMPBED)
-        case 304: // M304: Set bed PID parameters
-          gcode_M304();
-          break;
-      #endif // PIDTEMPBED
+        case 304: M304(); break;  // M304: Set bed PID parameters
+      #endif
 
       #if defined(CHDK) || HAS_PHOTOGRAPH
         case 240: // M240: Trigger a camera by emulating a Canon RC-1 : http://www.doc-diy.net/photo/rc-1_hacked/