diff --git a/Eigen/src/Geometry/Rotation2D.h b/Eigen/src/Geometry/Rotation2D.h
index 3e0ea3c62..dca7f06bf 100644
--- a/Eigen/src/Geometry/Rotation2D.h
+++ b/Eigen/src/Geometry/Rotation2D.h
@@ -85,7 +85,7 @@ public:
 
   /** Concatenates two rotations */
   inline Rotation2D& operator*=(const Rotation2D& other)
-  { return m_angle += other.m_angle; }
+  { return m_angle += other.m_angle; return *this; }
 
   /** Applies the rotation to a 2D vector */
   Vector2 operator* (const Vector2& vec) const