diff --git a/variants/STM32F4xx/F401R(B-C-D-E)T/variant_NUCLEO_F401RE.cpp b/variants/STM32F4xx/F401R(B-C-D-E)T/variant_NUCLEO_F401RE.cpp
index 6ce1dc5152..6a4009735c 100644
--- a/variants/STM32F4xx/F401R(B-C-D-E)T/variant_NUCLEO_F401RE.cpp
+++ b/variants/STM32F4xx/F401R(B-C-D-E)T/variant_NUCLEO_F401RE.cpp
@@ -115,12 +115,13 @@ WEAK void SystemClock_Config(void)
   __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE2);
 
   /* Initializes the CPU, AHB and APB busses clocks */
-  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
-  RCC_OscInitStruct.HSEState = RCC_HSE_BYPASS;
+  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
+  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
+  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
   RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
-  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
+  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
   RCC_OscInitStruct.PLL.PLLM = 8;
-  RCC_OscInitStruct.PLL.PLLN = 336;
+  RCC_OscInitStruct.PLL.PLLN = 168;
   RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV4;
   RCC_OscInitStruct.PLL.PLLQ = 7;