diff --git a/lib/stm32/f3/adc.c b/lib/stm32/f3/adc.c
index 3a4d3869..ae4210c8 100644
--- a/lib/stm32/f3/adc.c
+++ b/lib/stm32/f3/adc.c
@@ -1026,8 +1026,8 @@ bool adc_get_overrun_flag(uint32_t adc)
 
 void adc_clear_overrun_flag(uint32_t adc)
 {
-/* need to write zero to clear this */
-	ADC_ISR(adc) &= ~ADC_ISR_OVR;
+	/* r_w1 bit */
+	ADC_ISR(adc) |= ADC_ISR_OVR;
 }
 
 /*---------------------------------------------------------------------------*/