diff --git a/os/hal/ports/STM32/LLD/ADCv4/hal_adc_lld.c b/os/hal/ports/STM32/LLD/ADCv4/hal_adc_lld.c
index cebb1df45..af93dd13d 100644
--- a/os/hal/ports/STM32/LLD/ADCv4/hal_adc_lld.c
+++ b/os/hal/ports/STM32/LLD/ADCv4/hal_adc_lld.c
@@ -551,7 +551,7 @@ void adc_lld_stop(ADCDriver *adcp) {
  * @notapi
  */
 void adc_lld_start_conversion(ADCDriver *adcp) {
-  uint32_t dmamode, cfgr;
+  uint32_t dmamode, cfgr = 0U;
   const ADCConversionGroup *grpp = adcp->grpp;
 
 #if STM32_ADC_USE_ADC12 == TRUE
diff --git a/readme.txt b/readme.txt
index dd871da89..33357daa7 100644
--- a/readme.txt
+++ b/readme.txt
@@ -76,6 +76,7 @@
 *** 20.3.4 ***
 - NEW: Files mcuconf.h for STM32F746, F767, L432, L452, L476, L496 received
        the missing setting STM32_WSPI_QUADSPI1_PRESCALER_VALUE.
+- FIX: Fixed warning in STM32 ADCv4 (bug #1158).
 - FIX: Fixed wrong check on HAL_USE_RTC in STM32G4 clock initialization
        (bug #1157).
 - FIX: Fixed wrong checks related to PLLSAI2 on L4 and L4+ (bug #1156).