diff --git a/libraries/AP_GPS/AP_GPS.cpp b/libraries/AP_GPS/AP_GPS.cpp
index ca1ab2a3b9..2223766edb 100644
--- a/libraries/AP_GPS/AP_GPS.cpp
+++ b/libraries/AP_GPS/AP_GPS.cpp
@@ -1383,7 +1383,7 @@ void AP_GPS::calc_blended_state(void)
 
     // Calculate ground speed and course from blended velocity vector
     state[GPS_BLENDED_INSTANCE].ground_speed = norm(state[GPS_BLENDED_INSTANCE].velocity.x, state[GPS_BLENDED_INSTANCE].velocity.y);
-    state[GPS_BLENDED_INSTANCE].ground_course = wrap_360(degrees(atan2f(state[GPS_BLENDED_INSTANCE].velocity.x, state[GPS_BLENDED_INSTANCE].velocity.x)));
+    state[GPS_BLENDED_INSTANCE].ground_course = wrap_360(degrees(atan2f(state[GPS_BLENDED_INSTANCE].velocity.y, state[GPS_BLENDED_INSTANCE].velocity.x)));
 
     /*
      * The blended location in _output_state.location is not stable enough to be used by the autopilot