diff --git a/cpp/sopt/real_indicator.h b/cpp/sopt/real_indicator.h
index 8c16630b9..c0f532149 100644
--- a/cpp/sopt/real_indicator.h
+++ b/cpp/sopt/real_indicator.h
@@ -40,8 +40,10 @@ class RealIndicator : public NonDifferentiableFunc<SCALAR>
     // should not be used in this case
     t_LinearTransform const &Psi() const override
     {
-        return sopt::linear_transform_identity<SCALAR>();
+        return linear_operator;
     }
+
+    t_LinearTransform linear_operator = sopt::linear_transform_identity<SCALAR>();
 };
 
 template<>