diff --git a/Marlin/pins_K8400.h b/Marlin/pins_K8400.h
index 030546c93..1ef8049c1 100644
--- a/Marlin/pins_K8400.h
+++ b/Marlin/pins_K8400.h
@@ -65,3 +65,4 @@
 //
 #undef PS_ON_PIN
 #undef KILL_PIN
+#undef SD_DETECT_PIN