diff --git a/libraries/AP_Math/quaternion.h b/libraries/AP_Math/quaternion.h
index ddf35ebbbc..c8d4bd2131 100644
--- a/libraries/AP_Math/quaternion.h
+++ b/libraries/AP_Math/quaternion.h
@@ -40,6 +40,12 @@ public:
     {
     }
 
+    // setting constructor
+    Quaternion(const float _q[4]) :
+        q1(_q[0]), q2(_q[1]), q3(_q[2]), q4(_q[3])
+    {
+    }
+
     // function call operator
     void operator()(const float _q1, const float _q2, const float _q3, const float _q4)
     {