diff --git a/src/nodes.jl b/src/nodes.jl
index ee1633c5..481339e9 100644
--- a/src/nodes.jl
+++ b/src/nodes.jl
@@ -58,6 +58,7 @@ function NodeSet(nodes::AbstractVector{RealT}) where {RealT}
     @assert length(nodes) > 0
     return NodeSet([[node] for node in nodes])
 end
+NodeSet(nodeset::NodeSet) = nodeset
 
 """
     empty_nodeset(Dim, RealT = Float64)
@@ -119,9 +120,11 @@ end
 function Base.similar(nodeset::NodeSet{Dim, RealT}, ::Type{T}, n::Int) where {Dim, RealT, T}
     NodeSet{Dim, T}(similar(nodeset.nodes, MVector{Dim, T}, n), Inf)
 end
-Base.getindex(nodeset::NodeSet, i::Int) = getindex(nodeset.nodes, i)
-Base.getindex(nodeset::NodeSet, is::UnitRange) = nodeset.nodes[is]
+Base.getindex(nodeset::NodeSet, i::Int) = nodeset.nodes[i]
+Base.getindex(nodeset::NodeSet, is::AbstractVector) = nodeset.nodes[is]
+Base.firstindex(nodeset::NodeSet) = firstindex(nodeset.nodes)
 Base.lastindex(nodeset::NodeSet) = lastindex(nodeset.nodes)
+Base.keys(nodeset::NodeSet) = keys(nodeset.nodes)
 function Base.setindex!(nodeset::NodeSet{Dim, RealT}, v::MVector{Dim, RealT},
                         i::Int) where {Dim, RealT}
     nodeset.nodes[i] = v
@@ -190,11 +193,10 @@ Compute the distance matrix between two [`NodeSet`](@ref)s, which is a matrix ``
 `nodeset1` and ``\xi_j`` are the nodes on `nodeset2`.
 """
 function distance_matrix(nodeset1::NodeSet, nodeset2::NodeSet)
-    n1 = length(nodeset1)
-    n2 = length(nodeset2)
-    D = zeros(n1, n2)
-    for i in 1:n1
-        for j in 1:n2
+    n1, n2 = length(nodeset1), length(nodeset2)
+    D = zeros(eltype(nodeset1), n1, n2)
+    for i in eachindex(nodeset1)
+        for j in eachindex(nodeset2)
             D[i, j] = norm(nodeset1[i] - nodeset2[j])
         end
     end
diff --git a/test/test_unit.jl b/test/test_unit.jl
index 658ccbb9..b9c3d9b9 100644
--- a/test/test_unit.jl
+++ b/test/test_unit.jl
@@ -197,6 +197,7 @@ end
                                      1.0 0.0
                                      0.0 1.0
                                      1.0 1.0])
+    @test NodeSet(nodeset1) == nodeset1
     @test_nowarn println(nodeset1)
     @test_nowarn display(nodeset1)
     @test eltype(nodeset1) == Float64
@@ -205,7 +206,8 @@ end
     @test length(nodeset1) == 4
     @test size(nodeset1) == (4, 2)
     @test axes(nodeset1) == (1:4,)
-    @test eachindex(nodeset1) == 1:4
+    @test eachindex(nodeset1) == firstindex(nodeset1):lastindex(nodeset1)
+    @test keys(nodeset1) == 1:4
     for node in nodeset1
         @test node isa MVector{2, Float64}
     end