diff --git a/os/hal/ports/STM32/STM32F37x/hal_adc_lld.h b/os/hal/ports/STM32/STM32F37x/hal_adc_lld.h
index d78389e30..ddea23640 100644
--- a/os/hal/ports/STM32/STM32F37x/hal_adc_lld.h
+++ b/os/hal/ports/STM32/STM32F37x/hal_adc_lld.h
@@ -35,7 +35,7 @@
  * @name    Triggers selection
  * @{
  */
-#define ADC_CR2_EXTSEL_SRC(n)   ((n) << 24) /**< @brief Trigger source.     */
+#define ADC_CR2_EXTSEL_SRC(n)   ((n) << 17) /**< @brief Trigger source.     */
 /** @} */
 
 /**
diff --git a/readme.txt b/readme.txt
index 6ee83650a..c87ec5a18 100644
--- a/readme.txt
+++ b/readme.txt
@@ -147,6 +147,8 @@
 - RT:  Merged RT4.
 - NIL: Merged NIL2.
 - NIL: Added STM32F7 demo.
+- HAL: Fixed wrong bit offset in STM32F37x ADC_CR2_EXTSEL_SRC() macro
+       (bug #785)(backported to 16.1.6, 3.0.6).
 - RT:  Fixed tick-less mode can fail in RT for very large delays (bug #784)
        (backported to 16.1.6, 3.0.6).
 - HAL: Fixed STM32L0xx CCIPR initialization (bug #783)