diff --git a/cpp/Point2.h b/cpp/Point2.h
index de9fe6ba4..ddb9c47de 100644
--- a/cpp/Point2.h
+++ b/cpp/Point2.h
@@ -47,6 +47,7 @@ namespace gtsam {
     Vector vector() const { return Vector_(2, x_, y_); }
 
     /** operators */
+    inline Point2 operator- () const {return Point2(-x_,-y_);}
     inline bool   operator ==(const Point2& q) const {return x_==q.x_ && q.y_==q.y_;}
     inline Point2 operator + (const Point2& q) const {return Point2(x_+q.x_,y_+q.y_);}
     inline Point2 operator - (const Point2& q) const {return Point2(x_-q.x_,y_-q.y_);}