diff --git a/Project.toml b/Project.toml
index 24fcf73..e0513bf 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "DiagonalArrays"
 uuid = "74fd4be6-21e2-4f6f-823a-4360d37c7a77"
 authors = ["ITensor developers <support@itensor.org> and contributors"]
-version = "0.2.6"
+version = "0.3.0"
 
 [deps]
 ArrayLayouts = "4c555306-a7a7-4459-81d9-ec55ddd5c99a"
diff --git a/docs/Project.toml b/docs/Project.toml
index 92b001e..228ca1b 100644
--- a/docs/Project.toml
+++ b/docs/Project.toml
@@ -4,6 +4,6 @@ Documenter = "e30172f5-a6a5-5a46-863b-614d45cd2de4"
 Literate = "98b081ad-f1c9-55d3-8b20-4c87d4299306"
 
 [compat]
-DiagonalArrays = "0.2"
+DiagonalArrays = "0.3"
 Documenter = "1"
 Literate = "2"
diff --git a/examples/Project.toml b/examples/Project.toml
index df0fc98..b559d07 100644
--- a/examples/Project.toml
+++ b/examples/Project.toml
@@ -3,5 +3,5 @@ DiagonalArrays = "74fd4be6-21e2-4f6f-823a-4360d37c7a77"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [compat]
-DiagonalArrays = "0.2"
+DiagonalArrays = "0.3"
 Test = "1"
diff --git a/src/diagonalarray/diagonalarray.jl b/src/diagonalarray/diagonalarray.jl
index fcb098e..a7358c8 100644
--- a/src/diagonalarray/diagonalarray.jl
+++ b/src/diagonalarray/diagonalarray.jl
@@ -2,90 +2,103 @@ function getzero(a::AbstractArray{<:Any,N}, I::Vararg{Int,N}) where {N}
   return zero(eltype(a))
 end
 
+function _DiagonalArray end
+
 struct DiagonalArray{T,N,Diag<:AbstractVector{T},F} <: AbstractDiagonalArray{T,N}
   diag::Diag
-  dims::NTuple{N,Int}
-  getunstoredindex::F
+  dims::Dims{N}
+  getunstored::F
+  global @inline function _DiagonalArray(
+    diag::Diag, dims::Dims{N}, getunstored::F
+  ) where {T,N,Diag<:AbstractVector{T},F}
+    all(≥(0), dims) || throw(ArgumentError("Invalid dimensions: $dims"))
+    length(diag) == minimum(dims) ||
+      throw(ArgumentError("Length of diagonals doesn't match dimensions"))
+    return new{T,N,Diag,F}(diag, dims, getunstored)
+  end
 end
 
 function DiagonalArray{T,N}(
-  diag::AbstractVector{T}, d::Tuple{Vararg{Int,N}}, getunstoredindex=getzero
+  diag::AbstractVector, dims::Dims{N}; getunstored=getzero
 ) where {T,N}
-  return DiagonalArray{T,N,typeof(diag),typeof(getunstoredindex)}(diag, d, getunstoredindex)
+  return _DiagonalArray(convert(AbstractVector{T}, diag), dims, getunstored)
 end
 
 function DiagonalArray{T,N}(
-  diag::AbstractVector, d::Tuple{Vararg{Int,N}}, getunstoredindex=getzero
+  diag::AbstractVector, dims::Vararg{Int,N}; kwargs...
 ) where {T,N}
-  return DiagonalArray{T,N}(T.(diag), d, getunstoredindex)
+  return DiagonalArray{T,N}(diag, dims; kwargs...)
 end
 
-function DiagonalArray{T,N}(diag::AbstractVector, d::Vararg{Int,N}) where {T,N}
-  return DiagonalArray{T,N}(diag, d)
+function DiagonalArray{T}(diag::AbstractVector, dims::Dims{N}; kwargs...) where {T,N}
+  return DiagonalArray{T,N}(diag, dims; kwargs...)
 end
 
-function DiagonalArray{T}(
-  diag::AbstractVector, d::Tuple{Vararg{Int,N}}, getunstoredindex=getzero
+function DiagonalArray{T}(diag::AbstractVector, dims::Vararg{Int,N}; kwargs...) where {T,N}
+  return DiagonalArray{T,N}(diag, dims; kwargs...)
+end
+
+function DiagonalArray{<:Any,N}(
+  diag::AbstractVector{T}, dims::Dims{N}; kwargs...
 ) where {T,N}
-  return DiagonalArray{T,N}(diag, d, getunstoredindex)
+  return DiagonalArray{T,N}(diag, dims; kwargs...)
 end
 
-function DiagonalArray{T}(diag::AbstractVector, d::Vararg{Int,N}) where {T,N}
-  return DiagonalArray{T,N}(diag, d)
+function DiagonalArray{<:Any,N}(
+  diag::AbstractVector{T}, dims::Vararg{Int,N}; kwargs...
+) where {T,N}
+  return DiagonalArray{T,N}(diag, dims; kwargs...)
 end
 
-function DiagonalArray(diag::AbstractVector{T}, d::Tuple{Vararg{Int,N}}) where {T,N}
-  return DiagonalArray{T,N}(diag, d)
+function DiagonalArray(diag::AbstractVector{T}, dims::Dims{N}; kwargs...) where {T,N}
+  return DiagonalArray{T,N}(diag, dims; kwargs...)
 end
 
-function DiagonalArray(diag::AbstractVector{T}, d::Vararg{Int,N}) where {T,N}
-  return DiagonalArray{T,N}(diag, d)
+function DiagonalArray(diag::AbstractVector{T}, dims::Vararg{Int,N}; kwargs...) where {T,N}
+  return DiagonalArray{T,N}(diag, dims; kwargs...)
 end
 
 # Infer size from diagonal
-function DiagonalArray{T,N}(diag::AbstractVector) where {T,N}
-  return DiagonalArray{T,N}(diag, ntuple(Returns(length(diag)), N))
+function DiagonalArray{T,N}(diag::AbstractVector; kwargs...) where {T,N}
+  return DiagonalArray{T,N}(diag, ntuple(Returns(length(diag)), N); kwargs...)
 end
 
-function DiagonalArray{<:Any,N}(diag::AbstractVector{T}) where {T,N}
-  return DiagonalArray{T,N}(diag)
+function DiagonalArray{<:Any,N}(diag::AbstractVector{T}; kwargs...) where {T,N}
+  return DiagonalArray{T,N}(diag; kwargs...)
 end
 
 # undef
-function DiagonalArray{T,N}(
-  ::UndefInitializer, d::Tuple{Vararg{Int,N}}, getunstoredindex=getzero
-) where {T,N}
-  return DiagonalArray{T,N}(Vector{T}(undef, minimum(d)), d, getunstoredindex)
+function DiagonalArray{T,N}(::UndefInitializer, dims::Dims{N}; kwargs...) where {T,N}
+  return DiagonalArray{T,N}(Vector{T}(undef, minimum(dims)), dims; kwargs...)
 end
 
-function DiagonalArray{T,N}(::UndefInitializer, d::Vararg{Int,N}) where {T,N}
-  return DiagonalArray{T,N}(undef, d)
+function DiagonalArray{T,N}(::UndefInitializer, dims::Vararg{Int,N}; kwargs...) where {T,N}
+  return DiagonalArray{T,N}(undef, dims; kwargs...)
 end
 
-function DiagonalArray{T}(
-  ::UndefInitializer, d::Tuple{Vararg{Int,N}}, getunstoredindex=getzero
-) where {T,N}
-  return DiagonalArray{T,N}(undef, d, getunstoredindex)
+function DiagonalArray{T}(::UndefInitializer, dims::Dims{N}; kwargs...) where {T,N}
+  return DiagonalArray{T,N}(undef, dims; kwargs...)
+end
+
+function DiagonalArray{T}(::UndefInitializer, dims::Vararg{Int,N}) where {T,N}
+  return DiagonalArray{T,N}(undef, dims)
 end
 
 # Axes version
 function DiagonalArray{T}(
-  ::UndefInitializer, axes::Tuple{Vararg{AbstractUnitRange,N}}, getunstoredindex=getzero
+  ::UndefInitializer, axes::NTuple{N,Base.OneTo{Int}}; kwargs...
 ) where {T,N}
-  @assert all(isone, first.(axes))
-  return DiagonalArray{T,N}(undef, length.(axes), getunstoredindex)
-end
-
-function DiagonalArray{T}(::UndefInitializer, d::Vararg{Int,N}) where {T,N}
-  return DiagonalArray{T,N}(undef, d)
+  return DiagonalArray{T,N}(undef, length.(axes); kwargs...)
 end
 
 # Minimal `AbstractArray` interface
 Base.size(a::DiagonalArray) = a.dims
 
 function Base.similar(a::DiagonalArray, elt::Type, dims::Tuple{Vararg{Int}})
-  # TODO: Preserve zero element function.
-  return DiagonalArray{elt}(undef, dims, a.getunstoredindex)
+  function getzero(a::AbstractArray{<:Any,N}, I::Vararg{Int,N}) where {N}
+    return convert(elt, a.getunstored(a, I...))
+  end
+  return DiagonalArray{elt}(undef, dims; getunstored=getzero)
 end
 
 # DiagonalArrays interface.
diff --git a/test/Project.toml b/test/Project.toml
index 053c41f..54990e4 100644
--- a/test/Project.toml
+++ b/test/Project.toml
@@ -10,7 +10,7 @@ Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [compat]
 Aqua = "0.8.9"
-DiagonalArrays = "0.2"
+DiagonalArrays = "0.3"
 FillArrays = "1"
 LinearAlgebra = "1"
 SafeTestsets = "0.1"