diff --git a/firmware/backlight.c b/firmware/backlight.c
index 3b58637362..98b2d9a40d 100644
--- a/firmware/backlight.c
+++ b/firmware/backlight.c
@@ -83,9 +83,7 @@ void backlight_start_timer(void)
         return ;
         
     /* Prevent cpu frequency changes while dimming. */
-#ifdef HAVE_ADJUSTABLE_CPU_FREQ
     cpu_boost(true);
-#endif    
     count = 1;
     bl_timer_active = true;
 
@@ -156,9 +154,7 @@ void TIMER1(void)
 
     if (idle) 
     {
-#ifdef HAVE_ADJUSTABLE_CPU_FREQ
-        cpu_boost(true);
-#endif    
+        cpu_boost(false);
         bl_timer_active = false;
         TMR1 = 0;
     }
@@ -180,9 +176,7 @@ void backlight_allow_timer(bool on)
 
     if (!timer_allowed && bl_timer_active)
     {
-#ifdef HAVE_ADJUSTABLE_CPU_FREQ
-        cpu_boost(true);
-#endif    
+        cpu_boost(false);
         bl_dim_current = bl_dim_target;
         bl_timer_active = false;
         TMR1 = 0;
diff --git a/firmware/export/system.h b/firmware/export/system.h
index bc54be3e1c..e98c362a8c 100644
--- a/firmware/export/system.h
+++ b/firmware/export/system.h
@@ -35,6 +35,7 @@ void set_cpu_frequency(long frequency);
 void cpu_boost(bool on_off);
 #else
 #define FREQ CPU_FREQ
+#define cpu_boost(on_off)
 #endif
 
 #define BAUDRATE 9600