diff --git a/libraries/AP_Math/vectorN.h b/libraries/AP_Math/vectorN.h
index 40c32ffd54f..1a78e7f36a2 100644
--- a/libraries/AP_Math/vectorN.h
+++ b/libraries/AP_Math/vectorN.h
@@ -171,6 +171,6 @@ public:
         }
     }
 
-private:
+protected:
     T _v[N];
 };