diff --git a/os/hal/platforms/STM32F4xx/hal_lld.c b/os/hal/platforms/STM32F4xx/hal_lld.c
index e3cf144e1..521a1723a 100644
--- a/os/hal/platforms/STM32F4xx/hal_lld.c
+++ b/os/hal/platforms/STM32F4xx/hal_lld.c
@@ -208,9 +208,14 @@ void stm32_clock_init(void) {
   RCC->CFGR |= STM32_MCO2PRE | STM32_MCO2SEL | STM32_MCO1PRE | STM32_MCO1SEL |
                STM32_RTCPRE | STM32_PPRE2 | STM32_PPRE1 | STM32_HPRE;
 
-  /* Flash setup.*/
-  FLASH->ACR = FLASH_ACR_PRFTEN | FLASH_ACR_ICEN | FLASH_ACR_DCEN |
-               STM32_FLASHBITS;
+  /* Flash setup.
+     Some old revisions of F4x MCUs randomly crashes with compiler
+     optimizations enabled AND flash caches enabled. */
+  if ((DBGMCU->IDCODE == 0x20006411) && (SCB->CPUID == 0x410FC241))
+    FLASH->ACR = FLASH_ACR_PRFTEN | STM32_FLASHBITS;
+  else
+    FLASH->ACR = FLASH_ACR_PRFTEN | FLASH_ACR_ICEN |
+                 FLASH_ACR_DCEN | STM32_FLASHBITS;
 
   /* Switching to the configured clock source if it is different from MSI.*/
 #if (STM32_SW != STM32_SW_HSI)
diff --git a/readme.txt b/readme.txt
index b63beac99..a31dcb240 100644
--- a/readme.txt
+++ b/readme.txt
@@ -82,6 +82,8 @@
 *****************************************************************************
 
 *** 2.5.1 ***
+- FIX: Fixed workaround for errata in STM32F4-A devices (bug 3586425)
+  (backported to 2.4.3).
 - FIX: Fixed error in palWritePad() macro (bug 3586230)(backported to 2.2.10
   and 2.4.3).
 - FIX: Fixed missing ; in testmbox.c (bug 3585979)(backported to 2.4.3).