diff --git a/sw/airborne/nav.c b/sw/airborne/nav.c
index b840d7efb8..80cdf2c1fb 100644
--- a/sw/airborne/nav.c
+++ b/sw/airborne/nav.c
@@ -58,6 +58,7 @@ float carrot_x, carrot_y;
 /** Status on the current circle */
 static float nav_circle_radians; /* Cumulated */
 float nav_circle_trigo_qdr; /* Angle from center to mobile */
+float nav_radius;
 
 
 /** Status on the current leg (percentage, 0. < < 1.) in route mode */
diff --git a/sw/airborne/nav.h b/sw/airborne/nav.h
index b324943aee..ee3b17c44a 100644
--- a/sw/airborne/nav.h
+++ b/sw/airborne/nav.h
@@ -110,6 +110,8 @@ extern float ground_alt;
 
 extern float survey_west, survey_east, survey_north, survey_south;
 
+extern float nav_radius;
+
 
 void nav_update(void);
 void nav_home(void);