diff --git a/Project.toml b/Project.toml
index 7092f35..eb5847e 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "DerivableInterfaces"
 uuid = "6c5e35bf-e59e-4898-b73c-732dcc4ba65f"
 authors = ["ITensor developers <support@itensor.org> and contributors"]
-version = "0.4.0"
+version = "0.4.1"
 
 [deps]
 Adapt = "79e6a3ab-5dfb-504d-930d-738a2a938a0e"
@@ -13,9 +13,16 @@ MLStyle = "d8e11817-5142-5d16-987a-aa16d5891078"
 MapBroadcast = "ebd9b9da-f48d-417c-9660-449667d60261"
 TypeParameterAccessors = "7e5a90cf-f82e-492e-a09b-e3e26432c138"
 
+[weakdeps]
+BlockArrays = "8e7c35d0-a365-5155-bbbb-fb81a777f24e"
+
+[extensions]
+DerivableInterfacesBlockArraysExt = "BlockArrays"
+
 [compat]
 Adapt = "4.1.1"
-ArrayLayouts = "1.11.0"
+ArrayLayouts = "1.11"
+BlockArrays = "1.4"
 Compat = "3.47,4.10"
 ExproniconLite = "0.10.13"
 LinearAlgebra = "1.10"
diff --git a/ext/DerivableInterfacesBlockArraysExt/DerivableInterfacesBlockArraysExt.jl b/ext/DerivableInterfacesBlockArraysExt/DerivableInterfacesBlockArraysExt.jl
new file mode 100644
index 0000000..000fe6b
--- /dev/null
+++ b/ext/DerivableInterfacesBlockArraysExt/DerivableInterfacesBlockArraysExt.jl
@@ -0,0 +1,10 @@
+module DerivableInterfacesBlockArraysExt
+
+using BlockArrays: BlockedOneTo, blockedrange, blocklengths
+using DerivableInterfaces.Concatenate: Concatenate
+
+function Concatenate.cat_axis(a1::BlockedOneTo, a2::BlockedOneTo)
+  return blockedrange([blocklengths(a1); blocklengths(a2)])
+end
+
+end
diff --git a/src/concatenate.jl b/src/concatenate.jl
index 01229d2..fcefee8 100644
--- a/src/concatenate.jl
+++ b/src/concatenate.jl
@@ -31,6 +31,11 @@ using Base: promote_eltypeof
 using ..DerivableInterfaces:
   DerivableInterfaces, AbstractInterface, interface, zero!, arraytype
 
+unval(x) = x
+unval(::Val{x}) where {x} = x
+
+function _Concatenated end
+
 """
     Concatenated{Interface,Dims,Args<:Tuple}
 
@@ -41,25 +46,25 @@ struct Concatenated{Interface,Dims,Args<:Tuple}
   interface::Interface
   dims::Val{Dims}
   args::Args
-
-  function Concatenated(
-    interface::Union{Nothing,AbstractInterface}, dims::Val{Dims}, args::Tuple
-  ) where {Dims}
-    return new{typeof(interface),Dims,typeof(args)}(interface, dims, args)
-  end
-  function Concatenated(dims, args::Tuple)
-    return Concatenated(interface(args...), dims, args)
-  end
-  function Concatenated{Interface}(dims, args) where {Interface}
-    return Concatenated(Interface(), dims, args)
-  end
-  function Concatenated{Interface,Dims}(args) where {Interface,Dims}
-    return new{Interface,Dims,typeof(args)}(Interface(), Val(Dims), args)
+  global @inline function _Concatenated(
+    interface::Interface, dims::Val{Dims}, args::Args
+  ) where {Interface,Dims,Args<:Tuple}
+    return new{Interface,Dims,Args}(interface, dims, args)
   end
 end
 
-dims(::Concatenated{A,D}) where {A,D} = D
-DerivableInterfaces.interface(concat::Concatenated) = concat.interface
+function Concatenated(interface::Union{Nothing,AbstractInterface}, dims::Val, args::Tuple)
+  return _Concatenated(interface, dims, args)
+end
+function Concatenated(dims::Val, args::Tuple)
+  return Concatenated(interface(args...), dims, args)
+end
+function Concatenated{Interface}(dims::Val, args::Tuple) where {Interface}
+  return Concatenated(Interface(), dims, args)
+end
+
+dims(::Concatenated{<:Any,D}) where {D} = D
+DerivableInterfaces.interface(concat::Concatenated) = getfield(concat, :interface)
 
 concatenated(dims, args...) = concatenated(Val(dims), args...)
 concatenated(dims::Val, args...) = Concatenated(dims, args)
@@ -80,13 +85,33 @@ function Base.similar(concat::Concatenated, ::Type{T}, ax) where {T}
   return similar(arraytype(interface(concat), T), ax)
 end
 
-Base.eltype(concat::Concatenated) = promote_eltypeof(concat.args...)
+function cat_axis(
+  a1::AbstractUnitRange, a2::AbstractUnitRange, a_rest::AbstractUnitRange...
+)
+  return cat_axis(cat_axis(a1, a2), a_rest...)
+end
+cat_axis(a1::AbstractUnitRange, a2::AbstractUnitRange) = Base.OneTo(length(a1) + length(a2))
 
-# For now, simply couple back to base implementation
-function Base.axes(concat::Concatenated)
-  catdims = Base.dims2cat(dims(concat))
-  return Base.cat_size_shape(catdims, concat.args...)
+function cat_ndims(dims, as::AbstractArray...)
+  return max(maximum(dims), maximum(ndims, as))
+end
+function cat_ndims(dims::Val, as::AbstractArray...)
+  return cat_ndims(unval(dims), as...)
+end
+
+function cat_axes(dims, a::AbstractArray, as::AbstractArray...)
+  return ntuple(cat_ndims(dims, a, as...)) do dim
+    return dim in dims ? cat_axis(map(Base.Fix2(axes, dim), (a, as...))...) : axes(a, dim)
+  end
 end
+function cat_axes(dims::Val, as::AbstractArray...)
+  return cat_axes(unval(dims), as...)
+end
+
+Base.eltype(concat::Concatenated) = promote_eltypeof(concat.args...)
+Base.axes(concat::Concatenated) = cat_axes(dims(concat), concat.args...)
+Base.size(concat::Concatenated) = length.(axes(concat))
+Base.ndims(concat::Concatenated) = length(axes(concat))
 
 # Main logic
 # ----------
@@ -122,19 +147,59 @@ Base.materialize!(dest, concat::Concatenated) = copyto!(dest, concat)
 
 Base.copy(concat::Concatenated) = copyto!(similar(concat), concat)
 
+# The following is largely copied from the Base implementation of `Base.cat`, see:
+# https://github.com/JuliaLang/julia/blob/885b1cd875f101f227b345f681cc36879124d80d/base/abstractarray.jl#L1778-L1887
+_copy_or_fill!(A, inds, x) = fill!(view(A, inds...), x)
+_copy_or_fill!(A, inds, x::AbstractArray) = (A[inds...] = x)
+
+cat_size(A) = (1,)
+cat_size(A::AbstractArray) = size(A)
+cat_size(A, d) = 1
+cat_size(A::AbstractArray, d) = size(A, d)
+
+cat_indices(A, d) = Base.OneTo(1)
+cat_indices(A::AbstractArray, d) = axes(A, d)
+
+function __cat!(A, shape, catdims, X...)
+  return __cat_offset!(A, shape, catdims, ntuple(zero, length(shape)), X...)
+end
+function __cat_offset!(A, shape, catdims, offsets, x, X...)
+  # splitting the "work" on x from X... may reduce latency (fewer costly specializations)
+  newoffsets = __cat_offset1!(A, shape, catdims, offsets, x)
+  return __cat_offset!(A, shape, catdims, newoffsets, X...)
+end
+__cat_offset!(A, shape, catdims, offsets) = A
+function __cat_offset1!(A, shape, catdims, offsets, x)
+  inds = ntuple(length(offsets)) do i
+    (i <= length(catdims) && catdims[i]) ? offsets[i] .+ cat_indices(x, i) : 1:shape[i]
+  end
+  _copy_or_fill!(A, inds, x)
+  newoffsets = ntuple(length(offsets)) do i
+    (i <= length(catdims) && catdims[i]) ? offsets[i] + cat_size(x, i) : offsets[i]
+  end
+  return newoffsets
+end
+
+dims2cat(dims::Val) = dims2cat(unval(dims))
+function dims2cat(dims)
+  if any(≤(0), dims)
+    throw(ArgumentError("All cat dimensions must be positive integers, but got $dims"))
+  end
+  return ntuple(in(dims), maximum(dims))
+end
+
 # default falls back to replacing interface with Nothing
 # this permits specializing on typeof(dest) without ambiguities
 # Note: this needs to be defined for AbstractArray specifically to avoid ambiguities with Base.
-@inline Base.copyto!(dest::AbstractArray, concat::Concatenated) =
-  copyto!(dest, convert(Concatenated{Nothing}, concat))
+@inline function Base.copyto!(dest::AbstractArray, concat::Concatenated)
+  return copyto!(dest, convert(Concatenated{Nothing}, concat))
+end
 
-# couple back to Base implementation if no specialization exists:
-# https://github.com/JuliaLang/julia/blob/29da86bb983066dd076439c2c7bc5e28dbd611bb/base/abstractarray.jl#L1852
 function Base.copyto!(dest::AbstractArray, concat::Concatenated{Nothing})
-  catdims = Base.dims2cat(dims(concat))
-  shape = Base.cat_size_shape(catdims, concat.args...)
+  catdims = dims2cat(dims(concat))
+  shape = size(concat)
   count(!iszero, catdims)::Int > 1 && zero!(dest)
-  return Base.__cat(dest, shape, catdims, concat.args...)
+  return __cat!(dest, shape, catdims, concat.args...)
 end
 
 end
diff --git a/src/defaultarrayinterface.jl b/src/defaultarrayinterface.jl
index bc2f9b6..538b8e7 100644
--- a/src/defaultarrayinterface.jl
+++ b/src/defaultarrayinterface.jl
@@ -30,3 +30,7 @@ end
 )
   return Base.mapreduce(f, op, as...; kwargs...)
 end
+
+function arraytype(::DefaultArrayInterface, T::Type)
+  return Array{T}
+end
diff --git a/src/zero.jl b/src/zero.jl
index d19cf35..d5c013c 100644
--- a/src/zero.jl
+++ b/src/zero.jl
@@ -4,3 +4,7 @@
 In-place version of `Base.zero`.
 """
 function zero! end
+
+@derive (T=AbstractArray,) begin
+  DerivableInterfaces.zero!(::T)
+end
diff --git a/test/test_concatenate.jl b/test/test_concatenate.jl
new file mode 100644
index 0000000..d35674b
--- /dev/null
+++ b/test/test_concatenate.jl
@@ -0,0 +1,31 @@
+using DerivableInterfaces.Concatenate: concatenated
+using Test: @test, @testset
+
+@testset "Concatenated" begin
+  a = randn(Float32, 2, 2)
+  b = randn(Float64, 2, 2)
+
+  concat = concatenated((1, 2), a, b)
+  @test axes(concat) == Base.OneTo.((4, 4))
+  @test size(concat) == (4, 4)
+  @test eltype(concat) === Float64
+  @test copy(concat) == cat(a, b; dims=(1, 2))
+
+  concat = concatenated(1, a, b)
+  @test axes(concat) == Base.OneTo.((4, 2))
+  @test size(concat) == (4, 2)
+  @test eltype(concat) === Float64
+  @test copy(concat) == cat(a, b; dims=1)
+
+  concat = concatenated(3, a, b)
+  @test axes(concat) == Base.OneTo.((2, 2, 2))
+  @test size(concat) == (2, 2, 2)
+  @test eltype(concat) === Float64
+  @test copy(concat) == cat(a, b; dims=3)
+
+  concat = concatenated(4, a, b)
+  @test axes(concat) == Base.OneTo.((2, 2, 1, 2))
+  @test size(concat) == (2, 2, 1, 2)
+  @test eltype(concat) === Float64
+  @test copy(concat) == cat(a, b; dims=4)
+end