diff --git a/EKF/common.h b/EKF/common.h
index 0320ad3ef3..dc3a73e53b 100644
--- a/EKF/common.h
+++ b/EKF/common.h
@@ -131,9 +131,9 @@ struct baroSample {
 };
 
 struct rangeSample {
-	float       rng;	///< range (distance to ground) measurement (m)
+	float       rng;	    ///< range (distance to ground) measurement (m)
 	uint64_t    time_us;	///< timestamp of the measurement (uSec)
-	uint8_t	    quality; ///< quality indicator between 0 and 255
+	int8_t	    quality;    ///< Signal quality in percent (0...100%), where 0 = invalid signal, 100 = perfect signal, and -1 = unknown signal quality.
 };
 
 struct airspeedSample {
diff --git a/EKF/estimator_interface.cpp b/EKF/estimator_interface.cpp
index 0de754677c..48c7782a25 100644
--- a/EKF/estimator_interface.cpp
+++ b/EKF/estimator_interface.cpp
@@ -314,7 +314,7 @@ void EstimatorInterface::setAirspeedData(uint64_t time_usec, float true_airspeed
 	}
 }
 
-void EstimatorInterface::setRangeData(uint64_t time_usec, float data, uint8_t quality)
+void EstimatorInterface::setRangeData(uint64_t time_usec, float data, int8_t quality)
 {
 	if (!_initialised || _range_buffer_fail) {
 		return;
diff --git a/EKF/estimator_interface.h b/EKF/estimator_interface.h
index bbd85dc005..869ea3a879 100644
--- a/EKF/estimator_interface.h
+++ b/EKF/estimator_interface.h
@@ -191,7 +191,7 @@ public:
 	void setAirspeedData(uint64_t time_usec, float true_airspeed, float eas2tas);
 
 	// set range data
-	void setRangeData(uint64_t time_usec, float data, uint8_t quality);
+	void setRangeData(uint64_t time_usec, float data, int8_t quality);
 
 	// set optical flow data
 	// if optical flow sensor gyro delta angles are not available, set gyroXYZ vector fields to NaN and the EKF will use its internal delta angle data instead