diff --git a/Project.toml b/Project.toml
index 90e50c4..6bf6f1e 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,6 +1,6 @@
 name = "OneHotArrays"
 uuid = "0b1bfda6-eb8a-41d2-88d8-f5af5cad476f"
-version = "0.2.8"
+version = "0.2.9"
 
 [deps]
 Adapt = "79e6a3ab-5dfb-504d-930d-738a2a938a0e"
@@ -17,7 +17,7 @@ ChainRulesCore = "1.13"
 Compat = "4.2"
 GPUArraysCore = "0.1, 0.2"
 NNlib = "0.8, 0.9"
-Zygote = "0.6.35"
+Zygote = "0.6.77, 0.7.7"
 julia = "1.6"
 
 [extras]
diff --git a/src/array.jl b/src/array.jl
index 45c91e9..2365c04 100644
--- a/src/array.jl
+++ b/src/array.jl
@@ -88,6 +88,20 @@ function Base.copyto!(dst::Array{T,N}, src::OneHotArray{<:Any,<:Any,N,<:AnyGPUAr
   copyto!(dst, adapt(Array, src))
 end
 
+@inline function Base.setindex!(x::OneHotArray{<:Any, N}, v, i::Integer, I::Vararg{Integer, N}) where N
+  @boundscheck checkbounds(x, i, I...)
+  if Bool(v)
+    @inbounds x.indices[I...] = i
+  elseif x.indices[I...] == i
+    # writing 0, at position of the 1 => move the 1 down if possible
+    i == x.nlabels && throw(ArgumentError("`setindex!` here would leave the `OneHotArray` without a hot one (in this column)"))
+    @inbounds x.indices[I...] = i+1
+  else
+    # writing 0, where it's already 0 => do nothing
+  end
+  x
+end
+
 function Base.showarg(io::IO, x::OneHotArray, toplevel)
   print(io, ndims(x) == 1 ? "OneHotVector(" : ndims(x) == 2 ? "OneHotMatrix(" : "OneHotArray(")
   Base.showarg(io, x.indices, false)
@@ -104,9 +118,9 @@ end
 # copy CuArray versions back before trying to print them:
 for fun in (:show, :print_array)  # print_array is used by 3-arg show
   @eval begin
-    Base.$fun(io::IO, X::OneHotLike{T, N, var"N+1", <:AbstractGPUArray}) where {T, N, var"N+1"} = 
+    Base.$fun(io::IO, X::OneHotLike{T, N, var"N+1", <:AbstractGPUArray}) where {T, N, var"N+1"} =
       Base.$fun(io, adapt(Array, X))
-    Base.$fun(io::IO, X::LinearAlgebra.AdjOrTrans{Bool, <:OneHotLike{T, N, <:Any, <:AbstractGPUArray}}) where {T, N} = 
+    Base.$fun(io::IO, X::LinearAlgebra.AdjOrTrans{Bool, <:OneHotLike{T, N, <:Any, <:AbstractGPUArray}}) where {T, N} =
       Base.$fun(io, adapt(Array, X))
   end
 end
diff --git a/test/array.jl b/test/array.jl
index 02db456..45424d6 100644
--- a/test/array.jl
+++ b/test/array.jl
@@ -49,6 +49,31 @@ end
   @test_throws BoundsError oa[:, :]
 end
 
+@testset "Writing" begin
+  x = onehotbatch([1,2,3], 0:4)
+  x[1] = 1
+  @test x[:, 1] == [1, 0, 0, 0, 0]
+  x[2, 1] = 1.0
+  @test x[:, 1] == [0, 1, 0, 0, 0]
+  x[2] = 0
+  @test x[:, 1] == [0, 0, 1, 0, 0]  # writing 0 pushes 1 down
+
+  y = onehotbatch([4,0,1], 0:4)
+  @test copyto!(x, y) == y
+  @test x[:, 1] == [0, 0, 0, 0, 1]
+  x .= 1
+  @test x[end, :] == [1, 1, 1]
+  x .= y
+  @test x[:, 3] == [0, 1, 0, 0, 0]
+
+  @test_throws ArgumentError y[5,1] = 0  # can't push 1 off the end
+  @test sum(y) == 3  # has not been corrupted before error
+
+  @test_throws BoundsError x[6,1] = 0
+  @test_throws BoundsError x[16] = 0
+  @test_throws InexactError x[2] = 1.5
+end
+
 @testset "Concatenating" begin
   # vector cat
   @test hcat(ov, ov) == OneHotMatrix(vcat(ov.indices, ov.indices), 10)