diff --git a/os/hal/ports/STM32/LLD/ADCv1/adc_lld.c b/os/hal/ports/STM32/LLD/ADCv1/adc_lld.c
index bd73a315f..2cb340e45 100644
--- a/os/hal/ports/STM32/LLD/ADCv1/adc_lld.c
+++ b/os/hal/ports/STM32/LLD/ADCv1/adc_lld.c
@@ -150,6 +150,14 @@ void adc_lld_init(void) {
 
   /* Calibration procedure.*/
   rccEnableADC1(FALSE);
+
+  /* CCR setup.*/
+#if STM32_ADC_SUPPORTS_PRESCALER
+  ADC->CCR = STM32_ADC_PRESC << 18;
+#else
+  ADC->CCR = 0;
+#endif
+
   osalDbgAssert(ADC1->CR == 0, "invalid register state");
   ADC1->CR |= ADC_CR_ADCAL;
   osalDbgAssert(ADC1->CR != 0, "invalid register state");
@@ -207,6 +215,13 @@ void adc_lld_stop(ADCDriver *adcp) {
 
     dmaStreamRelease(adcp->dmastp);
 
+    /* Restoring CCR default.*/
+#if STM32_ADC_SUPPORTS_PRESCALER
+    ADC->CCR = STM32_ADC_PRESC << 18;
+#else
+    ADC->CCR = 0;
+#endif
+
     /* Disabling ADC.*/
     if (adcp->adc->CR & ADC_CR_ADEN) {
       adc_lld_stop_adc(adcp->adc);
diff --git a/readme.txt b/readme.txt
index 3cffd8211..8ef07a213 100644
--- a/readme.txt
+++ b/readme.txt
@@ -96,6 +96,8 @@
 - RT:  Merged RT4.
 - NIL: Merged NIL2.
 - NIL: Added STM32F7 demo.
+- HAL: Fixed prescaler not initialized in STM32 ADCv1 (bug #725)
+       (backported to 16.1.5).
 - HAL: Fixed missing DAC section in STM32F072 mcuconf.h files (bug #724)
        (backported to 16.1.5).
 - VAR: Fixed palSetMode glitching outputs (bug #723)(backported to 3.0.6