diff --git a/src/Utils.jl b/src/Utils.jl
index 5215315d..8b4d29f7 100644
--- a/src/Utils.jl
+++ b/src/Utils.jl
@@ -3,14 +3,14 @@ export rownorm², nrmsd
 """
 This function computes the 2-norm² of a rows of S for dense matrices.
 """
-function rownorm²(B::Transpose{T,S},row::Int) where {T,S<:DenseMatrix}
+function rownorm²(B::Transpose{T,S},row::Int64) where {T,S<:DenseMatrix}
   A = B.parent
   U = real(eltype(A))
   res::U = BLAS.nrm2(size(A,1), pointer(A,(LinearIndices(size(A)))[1,row]), 1)^2
   return res
 end
 
-function rownorm²(A::AbstractMatrix,row::Int)
+function rownorm²(A::AbstractMatrix,row::Int64)
   T = real(eltype(A))
   res = zero(T)
   @simd for n=1:size(A,2)
@@ -19,19 +19,27 @@ function rownorm²(A::AbstractMatrix,row::Int)
   return res
 end
 
-rownorm²(A::AbstractLinearOperator,row) = rownorm²(Matrix(A[row, :]), 1)
-rownorm²(A::ProdOp{T, <:WeightingOp, matT}, row) where {T, matT} = A.A.weights[row]^2*rownorm²(A.B, row)
+rownorm²(A::AbstractLinearOperator,row::Int64) = rownorm²(Matrix(A[row, :]), 1)
+rownorm²(A::ProdOp{T, <:WeightingOp, matT}, row::Int64) where {T, matT} = A.A.weights[row]^2*rownorm²(A.B, row)
 
 """
 This function computes the 2-norm² of a rows of S for sparse matrices.
 """
-function rownorm²(B::Transpose{T,S},row::Int) where {T,S<:SparseMatrixCSC}
+function rownorm²(B::Transpose{T,S},row::Int64) where {T,S<:SparseMatrixCSC}
   A = B.parent
   U = real(eltype(A))
   res::U = BLAS.nrm2(A.colptr[row+1]-A.colptr[row], pointer(A.nzval,A.colptr[row]), 1)^2
   return res
 end
 
+function rownorm²(A, rows)
+  res = zero(real(eltype(A)))
+  @simd for row in rows
+    res += rownorm²(A, row)
+  end
+  return res
+end
+
 
 ### dot_with_matrix_row ###