diff --git a/boards/airfy-beacon/include/periph_conf.h b/boards/airfy-beacon/include/periph_conf.h
index f10fc2d679..bd35bc4ed9 100644
--- a/boards/airfy-beacon/include/periph_conf.h
+++ b/boards/airfy-beacon/include/periph_conf.h
@@ -86,8 +86,9 @@ static const i2c_conf_t i2c_config[] = {
  * The configuration consists simply of a list of channels that should be used
  * @{
  */
-#define ADC_CONFIG          {3, 4, 5, 6}
-#define ADC_NUMOF           (4)
+static const adc_conf_t adc_config[] = {3, 4, 5, 6};
+
+#define ADC_NUMOF           ARRAY_SIZE(adc_config)
 /** @} */
 
 #ifdef __cplusplus