diff --git a/platformio.ini b/platformio.ini
index 07ffbf91..47aca405 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -31,6 +31,8 @@ extends = arduino_base
 platform = espressif32
 monitor_filters = esp32_exception_decoder
 extra_scripts = merge-bin.py
+build_flags = ${arduino_base.build_flags}
+;  -D ESP32_CPU_FREQ=80          ; change it to your need
 build_src_filter = ${arduino_base.build_src_filter}
 
 ; ================
diff --git a/src/helpers/ESP32Board.h b/src/helpers/ESP32Board.h
index 45fb16bd..70e29575 100644
--- a/src/helpers/ESP32Board.h
+++ b/src/helpers/ESP32Board.h
@@ -17,6 +17,10 @@ public:
     // for future use, sub-classes SHOULD call this from their begin()
     startup_reason = BD_STARTUP_NORMAL;
 
+  #ifdef ESP32_CPU_FREQ
+    setCpuFrequencyMhz(ESP32_CPU_FREQ);
+  #endif
+
   #ifdef PIN_VBAT_READ
     // battery read support
     pinMode(PIN_VBAT_READ, INPUT);