diff --git a/Marlin/Configuration_adv.h b/Marlin/Configuration_adv.h
index b35745913d..c0cc264de3 100644
--- a/Marlin/Configuration_adv.h
+++ b/Marlin/Configuration_adv.h
@@ -79,7 +79,7 @@
 
   #define ADAPTIVE_FAN_SLOWING              // Slow part cooling fan if temperature drops
   #if ENABLED(ADAPTIVE_FAN_SLOWING) && ENABLED(PIDTEMP)
-    //#define NO_FAN_SLOWING_IN_PID_TUNING    // Don't slow fan speed during M303
+    #define NO_FAN_SLOWING_IN_PID_TUNING    // Don't slow fan speed during M303
   #endif
 
   /**