diff --git a/unsupported/Eigen/src/SparseExtra/BlockOfDynamicSparseMatrix.h b/unsupported/Eigen/src/SparseExtra/BlockOfDynamicSparseMatrix.h
index fd24a732d..e9ec746e3 100644
--- a/unsupported/Eigen/src/SparseExtra/BlockOfDynamicSparseMatrix.h
+++ b/unsupported/Eigen/src/SparseExtra/BlockOfDynamicSparseMatrix.h
@@ -12,6 +12,12 @@
 
 namespace Eigen { 
 
+#if 0
+
+// NOTE Have to be reimplemented as a specialization of BlockImpl< DynamicSparseMatrix<_Scalar, _Options, _Index>, ... >
+// See SparseBlock.h for an example
+
+
 /***************************************************************************
 * specialisation for DynamicSparseMatrix
 ***************************************************************************/
@@ -109,6 +115,8 @@ class SparseInnerVectorSet<DynamicSparseMatrix<_Scalar, _Options, _Index>, Size>
 
 };
 
+#endif
+
 } // end namespace Eigen
 
 #endif // EIGEN_SPARSE_BLOCKFORDYNAMICMATRIX_H