diff --git a/ArduCopter/Parameters.h b/ArduCopter/Parameters.h
index 3363ce7138..1b9282104a 100644
--- a/ArduCopter/Parameters.h
+++ b/ArduCopter/Parameters.h
@@ -211,7 +211,7 @@ public:
 	AP_Float	low_voltage;
 	AP_Int8		super_simple;
 	AP_Int8		rtl_land_enabled;
-	AP_Uint8	rtl_approach_alt;
+	AP_Float	rtl_approach_alt;
 	AP_Int8		axis_enabled;
 	AP_Int8		copter_leds_mode;	// Operating mode of LED lighting system
 
@@ -332,7 +332,7 @@ public:
 	low_voltage				(LOW_VOLTAGE),
 	super_simple			(SUPER_SIMPLE),
 	rtl_land_enabled		(RTL_AUTO_LAND),
-	rtl_approach_alt		(0),
+	rtl_approach_alt		(0.0),
 	axis_enabled			(AXIS_LOCK_ENABLED),
 	copter_leds_mode		(0),