diff --git a/libraries/AP_Compass/AP_Compass.cpp b/libraries/AP_Compass/AP_Compass.cpp
index 540eb45d7d..2ecd6fc9d9 100644
--- a/libraries/AP_Compass/AP_Compass.cpp
+++ b/libraries/AP_Compass/AP_Compass.cpp
@@ -1769,7 +1769,7 @@ Compass::calculate_heading(const Matrix3f &dcm_matrix, uint8_t i) const
 
     // magnetic heading
     // 6/4/11 - added constrain to keep bad values from ruining DCM Yaw - Jason S.
-    float heading = constrain_float(atan2f(-headY,headX), -3.15f, 3.15f);
+    float heading = constrain_float(atan2f(-headY,headX), -M_PI, M_PI);
 
     // Declination correction (if supplied)
     if ( fabsf(_declination) > 0.0f ) {