diff --git a/Marlin/src/lcd/menu/menu_mmu2.h b/Marlin/src/lcd/menu/menu_mmu2.h
index 6c721e2941..5859d55911 100644
--- a/Marlin/src/lcd/menu/menu_mmu2.h
+++ b/Marlin/src/lcd/menu/menu_mmu2.h
@@ -23,6 +23,6 @@
 
 #include <stdint.h>
 
-extern void menu_mmu2();
-extern void mmu2_M600();
-extern uint8_t mmu2_chooseFilament();
+void menu_mmu2();
+void mmu2_M600();
+uint8_t mmu2_chooseFilament();