diff --git a/src/TNL/Matrices/Matrix.h b/src/TNL/Matrices/Matrix.h
index 48e6ebf7c59ce87f9ebcbda9a24c8014fe394baf..8e467b004fdda3971c509e3c1daa7f33e8ba8589 100644
--- a/src/TNL/Matrices/Matrix.h
+++ b/src/TNL/Matrices/Matrix.h
@@ -96,8 +96,8 @@ public:
    void copyFromHostToCuda( Matrices::Matrix< Real, Devices::Host, Index >& matrix );
 
    // TODO: missing implementation!
-   __cuda_callable__
-   Index getValuesSize() const;
+   //__cuda_callable__
+   //Index getValuesSize() const;
 
    protected: