diff --git a/flight/pios/stm32f4xx/libraries/CMSIS/Device/ST/STM32F4xx/Source/discoveryf4bare/system_stm32f4xx.c b/flight/pios/stm32f4xx/libraries/CMSIS/Device/ST/STM32F4xx/Source/discoveryf4bare/system_stm32f4xx.c
index e6ffcd777..cbc36d6e3 100644
--- a/flight/pios/stm32f4xx/libraries/CMSIS/Device/ST/STM32F4xx/Source/discoveryf4bare/system_stm32f4xx.c
+++ b/flight/pios/stm32f4xx/libraries/CMSIS/Device/ST/STM32F4xx/Source/discoveryf4bare/system_stm32f4xx.c
@@ -398,7 +398,7 @@ static void SetSysClock(void)
     }
    
     /* Configure Flash prefetch, Instruction cache, Data cache and wait state */
-    FLASH->ACR = FLASH_ACR_PRFTEN | FLASH_ACR_ICEN | FLASH_ACR_DCEN | FLASH_ACR_LATENCY_5WS;
+    FLASH->ACR = FLASH_ACR_ICEN |FLASH_ACR_DCEN |FLASH_ACR_LATENCY_5WS;
 
     /* Select the main PLL as system clock source */
     RCC->CFGR &= (uint32_t)((uint32_t)~(RCC_CFGR_SW));