diff --git a/libraries/mbed/targets/hal/TARGET_STM/TARGET_STM32F4/pwmout_api.c b/libraries/mbed/targets/hal/TARGET_STM/TARGET_STM32F4/pwmout_api.c
index 3820e46f1f..e6000c1bf6 100644
--- a/libraries/mbed/targets/hal/TARGET_STM/TARGET_STM32F4/pwmout_api.c
+++ b/libraries/mbed/targets/hal/TARGET_STM/TARGET_STM32F4/pwmout_api.c
@@ -241,9 +241,9 @@ void pwmout_period_us(pwmout_t* obj, int us)
 
     TimHandle.Init.Period        = us - 1;
     if (APBxCLKDivider == RCC_HCLK_DIV1)
-      TimHandle.Init.Prescaler   = (uint16_t)((PclkFreq*2) / 1000000) - 1; // 1 µs tick
+      TimHandle.Init.Prescaler   = (uint16_t)((PclkFreq) / 1000000) - 1; // 1 µs tick
     else
-      TimHandle.Init.Prescaler   = (uint16_t)((PclkFreq) / 1000000) - 1; // 1 µs tick
+      TimHandle.Init.Prescaler   = (uint16_t)((PclkFreq)*2 / 1000000) - 1; // 1 µs tick
     TimHandle.Init.ClockDivision = 0;
     TimHandle.Init.CounterMode   = TIM_COUNTERMODE_UP;
     HAL_TIM_PWM_Init(&TimHandle);