diff --git a/libraries/AC_AttitudeControl/AC_PosControl.cpp b/libraries/AC_AttitudeControl/AC_PosControl.cpp
index 387b788d2b..faf3be9ad0 100644
--- a/libraries/AC_AttitudeControl/AC_PosControl.cpp
+++ b/libraries/AC_AttitudeControl/AC_PosControl.cpp
@@ -1197,7 +1197,7 @@ void AC_PosControl::check_for_ekf_z_reset()
 bool AC_PosControl::limit_vector_length(float& vector_x, float& vector_y, float max_length)
 {
     float vector_length = norm(vector_x, vector_y);
-    if ((vector_length > max_length) && is_positive(max_length)) {
+    if ((vector_length > max_length) && is_positive(vector_length)) {
         vector_x *= (max_length / vector_length);
         vector_y *= (max_length / vector_length);
         return true;