diff --git a/Marlin/src/inc/Conditionals_post.h b/Marlin/src/inc/Conditionals_post.h
index a5c9d20eda..e1e82c40f2 100644
--- a/Marlin/src/inc/Conditionals_post.h
+++ b/Marlin/src/inc/Conditionals_post.h
@@ -2549,13 +2549,13 @@
 #endif
 
 // Thermal protection
-#if BOTH(HAS_HEATED_BED, THERMAL_PROTECTION_BED)
-  #define HAS_THERMALLY_PROTECTED_BED 1
+#if !HAS_HEATED_BED
+  #undef THERMAL_PROTECTION_BED
 #endif
 #if ENABLED(THERMAL_PROTECTION_HOTENDS) && WATCH_TEMP_PERIOD > 0
   #define WATCH_HOTENDS 1
 #endif
-#if HAS_THERMALLY_PROTECTED_BED && WATCH_BED_TEMP_PERIOD > 0
+#if ENABLED(THERMAL_PROTECTION_BED) && WATCH_BED_TEMP_PERIOD > 0
   #define WATCH_BED 1
 #endif
 #if BOTH(HAS_HEATED_CHAMBER, THERMAL_PROTECTION_CHAMBER) && WATCH_CHAMBER_TEMP_PERIOD > 0
@@ -2567,7 +2567,7 @@
 #if  (ENABLED(THERMAL_PROTECTION_HOTENDS) || !EXTRUDERS) \
   && (ENABLED(THERMAL_PROTECTION_BED)     || !HAS_HEATED_BED) \
   && (ENABLED(THERMAL_PROTECTION_CHAMBER) || !HAS_HEATED_CHAMBER) \
-  && (ENABLED(THERMAL_PROTECTION_COOLER) || !HAS_COOLER)
+  && (ENABLED(THERMAL_PROTECTION_COOLER)  || !HAS_COOLER)
   #define THERMALLY_SAFE 1
 #endif
 
diff --git a/Marlin/src/module/temperature.cpp b/Marlin/src/module/temperature.cpp
index dccdc55034..c5c4b3524b 100644
--- a/Marlin/src/module/temperature.cpp
+++ b/Marlin/src/module/temperature.cpp
@@ -1444,7 +1444,7 @@ void Temperature::manage_heater() {
 
       TERN_(HEATER_IDLE_HANDLER, heater_idle[IDLE_INDEX_BED].update(ms));
 
-      #if HAS_THERMALLY_PROTECTED_BED
+      #if ENABLED(THERMAL_PROTECTION_BED)
         tr_state_machine[RUNAWAY_IND_BED].run(temp_bed.celsius, temp_bed.target, H_BED, THERMAL_PROTECTION_BED_PERIOD, THERMAL_PROTECTION_BED_HYSTERESIS);
       #endif
 
@@ -2570,20 +2570,14 @@ void Temperature::init() {
       );
     */
 
-    #if HEATER_IDLE_HANDLER
-      // If the heater idle timeout expires, restart
-      if (heater_idle[idle_index].timed_out) {
-        state = TRInactive;
-        running_temp = 0;
-      }
-      else
-    #endif
-    {
-      // If the target temperature changes, restart
-      if (running_temp != target) {
-        running_temp = target;
-        state = target > 0 ? TRFirstHeating : TRInactive;
-      }
+    // If the heater idle timeout expires, restart
+    if (TERN0(HEATER_IDLE_HANDLER, heater_idle[idle_index].timed_out)) {
+      state = TRInactive;
+      running_temp = 0;
+    }
+    else if (running_temp != target) { // If the target temperature changes, restart
+      running_temp = target;
+      state = target > 0 ? TRFirstHeating : TRInactive;
     }
 
     switch (state) {
@@ -2596,7 +2590,7 @@ void Temperature::init() {
         state = TRStable;
 
       // While the temperature is stable watch for a bad temperature
-      case TRStable:
+      case TRStable: {
 
         #if ENABLED(ADAPTIVE_FAN_SLOWING)
           if (adaptive_fan_slowing && heater_id >= 0) {
@@ -2614,13 +2608,17 @@ void Temperature::init() {
           }
         #endif
 
+        const millis_t now = millis();
+
         if (current >= running_temp - hysteresis_degc) {
-          timer = millis() + SEC_TO_MS(period_seconds);
+          timer = now + SEC_TO_MS(period_seconds);
           break;
         }
-        else if (PENDING(millis(), timer)) break;
+        else if (PENDING(now, timer)) break;
         state = TRRunaway;
 
+      } // fall through
+
       case TRRunaway:
         TERN_(HAS_DWIN_E3V2_BASIC, DWIN_Popup_Temperature(0));
         _temp_error(heater_id, FPSTR(str_t_thermal_runaway), GET_TEXT_F(MSG_THERMAL_RUNAWAY));
diff --git a/Marlin/src/module/temperature.h b/Marlin/src/module/temperature.h
index 1ca0f3e88c..5661668204 100644
--- a/Marlin/src/module/temperature.h
+++ b/Marlin/src/module/temperature.h
@@ -1009,7 +1009,7 @@ class Temperature {
     static void min_temp_error(const heater_id_t e);
     static void max_temp_error(const heater_id_t e);
 
-    #define HAS_THERMAL_PROTECTION ANY(THERMAL_PROTECTION_HOTENDS, THERMAL_PROTECTION_CHAMBER, HAS_THERMALLY_PROTECTED_BED, THERMAL_PROTECTION_COOLER)
+    #define HAS_THERMAL_PROTECTION ANY(THERMAL_PROTECTION_HOTENDS, THERMAL_PROTECTION_CHAMBER, THERMAL_PROTECTION_BED, THERMAL_PROTECTION_COOLER)
 
     #if HAS_THERMAL_PROTECTION
 
@@ -1021,7 +1021,7 @@ class Temperature {
           REPEAT(HOTENDS, _RUNAWAY_IND_E)
           #undef _RUNAWAY_IND_E
         #endif
-        OPTARG(HAS_THERMALLY_PROTECTED_BED, RUNAWAY_IND_BED)
+        OPTARG(THERMAL_PROTECTION_BED, RUNAWAY_IND_BED)
         OPTARG(THERMAL_PROTECTION_CHAMBER, RUNAWAY_IND_CHAMBER)
         OPTARG(THERMAL_PROTECTION_COOLER, RUNAWAY_IND_COOLER)
         , NR_HEATER_RUNAWAY
@@ -1029,9 +1029,9 @@ class Temperature {
 
       // Convert the given heater_id_t to runaway state array index
       static RunawayIndex runaway_index_for_id(const int8_t heater_id) {
-        TERN_(HAS_THERMALLY_PROTECTED_CHAMBER, if (heater_id == H_CHAMBER) return RUNAWAY_IND_CHAMBER);
-        TERN_(HAS_THERMALLY_PROTECTED_CHAMBER, if (heater_id == H_COOLER)  return RUNAWAY_IND_COOLER);
-        TERN_(HAS_THERMALLY_PROTECTED_BED,     if (heater_id == H_BED)     return RUNAWAY_IND_BED);
+        TERN_(THERMAL_PROTECTION_CHAMBER, if (heater_id == H_CHAMBER) return RUNAWAY_IND_CHAMBER);
+        TERN_(THERMAL_PROTECTION_COOLER,  if (heater_id == H_COOLER)  return RUNAWAY_IND_COOLER);
+        TERN_(THERMAL_PROTECTION_BED,     if (heater_id == H_BED)     return RUNAWAY_IND_BED);
         return (RunawayIndex)_MAX(heater_id, 0);
       }