diff --git a/Marlin/src/inc/Conditionals_post.h b/Marlin/src/inc/Conditionals_post.h
index 7dc75db1c2..a6567e9714 100644
--- a/Marlin/src/inc/Conditionals_post.h
+++ b/Marlin/src/inc/Conditionals_post.h
@@ -2913,6 +2913,9 @@
   #define HAS_MULTI_SERIAL 1
 #endif
 
-#if ENABLED(MEATPACK_ON_SERIAL_PORT_1) || BOTH(HAS_MULTI_SERIAL, MEATPACK_ON_SERIAL_PORT_2)
+#if !HAS_MULTI_SERIAL
+  #undef MEATPACK_ON_SERIAL_PORT_2
+#endif
+#if EITHER(MEATPACK_ON_SERIAL_PORT_1, MEATPACK_ON_SERIAL_PORT_2)
   #define HAS_MEATPACK 1
 #endif