diff --git a/Marlin/src/HAL/STM32/fast_pwm.cpp b/Marlin/src/HAL/STM32/fast_pwm.cpp
index d28bc1b84b..2099184893 100644
--- a/Marlin/src/HAL/STM32/fast_pwm.cpp
+++ b/Marlin/src/HAL/STM32/fast_pwm.cpp
@@ -32,26 +32,17 @@ static uint16_t timer_freq[TIMER_NUM];
 
 void set_pwm_duty(const pin_t pin, const uint16_t v, const uint16_t v_size/*=255*/, const bool invert/*=false*/) {
   if (!PWM_PIN(pin)) return; // Don't proceed if no hardware timer
-  bool needs_freq;
   PinName pin_name = digitalPinToPinName(pin);
   TIM_TypeDef *Instance = (TIM_TypeDef *)pinmap_peripheral(pin_name, PinMap_PWM);
-  HardwareTimer *HT;
-  TimerModes_t previousMode;
 
-  uint16_t value = v;
-  if (invert) value = v_size - value;
-
-  uint32_t index = get_timer_index(Instance);
-
-  if (HardwareTimer_Handle[index] == nullptr) {
+  const uint32_t index = get_timer_index(Instance);
+  bool needs_freq = (HardwareTimer_Handle[index] == nullptr); // A new instance must be set to the default frequency of PWM_FREQUENCY
+  if (needs_freq)
     HardwareTimer_Handle[index]->__this = new HardwareTimer((TIM_TypeDef *)pinmap_peripheral(pin_name, PinMap_PWM));
-    needs_freq = true;                  // The instance must be new set the default frequency of PWM_FREQUENCY
-  }
-
-  HT = (HardwareTimer *)(HardwareTimer_Handle[index]->__this);
-  uint32_t channel = STM_PIN_CHANNEL(pinmap_function(pin_name, PinMap_PWM));
-  previousMode = HT->getMode(channel);
 
+  HardwareTimer * const HT = (HardwareTimer *)(HardwareTimer_Handle[index]->__this);
+  const uint32_t channel = STM_PIN_CHANNEL(pinmap_function(pin_name, PinMap_PWM));
+  const TimerModes_t previousMode = HT->getMode(channel);
   if (previousMode != TIMER_OUTPUT_COMPARE_PWM1)
     HT->setMode(channel, TIMER_OUTPUT_COMPARE_PWM1, pin);
 
@@ -63,6 +54,7 @@ void set_pwm_duty(const pin_t pin, const uint16_t v, const uint16_t v_size/*=255
   }
   // Note the resolution is sticky here, the input can be upto 16 bits and that would require RESOLUTION_16B_COMPARE_FORMAT (16)
   // If such a need were to manifest then we would need to calc the resolution based on the v_size parameter and add code for it.
+  const uint16_t value = invert ? v_size - v : v;
   HT->setCaptureCompare(channel, value, RESOLUTION_8B_COMPARE_FORMAT); // Sets the duty, the calc is done in the library :)
   pinmap_pinout(pin_name, PinMap_PWM); // Make sure the pin output state is set.
   if (previousMode != TIMER_OUTPUT_COMPARE_PWM1) HT->resume();
@@ -73,12 +65,12 @@ void set_pwm_frequency(const pin_t pin, int f_desired) {
 
   const PinName pin_name = digitalPinToPinName(pin);
   TIM_TypeDef * const Instance = (TIM_TypeDef *)pinmap_peripheral(pin_name, PinMap_PWM); // Get HAL timer instance
-  uint32_t index = get_timer_index(Instance);
+  const uint32_t index = get_timer_index(Instance);
 
   // Protect used timers
-  if (index == TEMP_TIMER_NUM || index == STEP_TIMER_NUM
-    #if PULSE_TIMER_NUM != STEP_TIMER_NUM
-      || index == PULSE_TIMER_NUM
+  if (index == MF_TIMER_TEMP || index == MF_TIMER_STEP
+    #if MF_TIMER_PULSE != MF_TIMER_STEP
+      || index == MF_TIMER_PULSE
     #endif
   ) return;