diff --git a/src/TNL/Matrices/CSR.h b/src/TNL/Matrices/CSR.h
index e4564562522765f1806846c4a619a049ec3f768b..10b7184569e80ceaea1b560dd39142e9098c672b 100644
--- a/src/TNL/Matrices/CSR.h
+++ b/src/TNL/Matrices/CSR.h
@@ -82,11 +82,12 @@ public:
 
    __cuda_callable__
    IndexType getRowLengthFast( const IndexType row ) const;
-   
+
    IndexType getNonZeroRowLength( const IndexType row ) const;
-   
+
+   __cuda_callable__
    IndexType getNonZeroRowLengthFast( const IndexType row ) const;
-   
+
    template< typename Real2, typename Device2, typename Index2 >
    void setLike( const CSR< Real2, Device2, Index2 >& matrix );