diff --git a/Marlin/src/inc/SanityCheck.h b/Marlin/src/inc/SanityCheck.h
index 45cda8081c..f07445f156 100644
--- a/Marlin/src/inc/SanityCheck.h
+++ b/Marlin/src/inc/SanityCheck.h
@@ -879,6 +879,7 @@ static_assert(Y_MAX_LENGTH >= Y_BED_SIZE, "Movement bounds (Y_MIN_POS, Y_MAX_POS
  */
 #if HAS_PRUSA_MMU2
   #if EXTRUDERS != 5
+    #undef SINGLENOZZLE
     #error "PRUSA_MMU2(S) requires exactly 5 EXTRUDERS. Please update your Configuration."
   #elif DISABLED(NOZZLE_PARK_FEATURE)
     #error "PRUSA_MMU2(S) requires NOZZLE_PARK_FEATURE. Enable it to continue."