diff --git a/libraries/AP_ADC/AP_ADC_ADS1115.h b/libraries/AP_ADC/AP_ADC_ADS1115.h
index 98e6544875..5eca42666b 100644
--- a/libraries/AP_ADC/AP_ADC_ADS1115.h
+++ b/libraries/AP_ADC/AP_ADC_ADS1115.h
@@ -31,7 +31,6 @@ private:
 
     AP_HAL::OwnPtr<AP_HAL::I2CDevice> _dev;
 
-    uint32_t            _last_update_timestamp;
     uint16_t            _gain;
     int                 _channel_to_read;
     adc_report_s        *_samples;