diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 05217e81..9af14c6a 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -5,7 +5,7 @@ variables:
   CI_IMAGE_TAG: 'cuda'
 
 include:
-  - 'https://raw.githubusercontent.com/JuliaGPU/gitlab-ci/master/templates/v3/common.yml'
+  - 'https://raw.githubusercontent.com/JuliaGPU/gitlab-ci/master/templates/v4/common.yml'
 
 .flux:
   extends: .test
@@ -13,25 +13,39 @@ include:
     - julia -e 'using InteractiveUtils;
                 versioninfo()'
     - mkdir $JULIA_DEPOT_PATH # Pkg3.jl#325
-    - julia -e 'using Pkg;
-                Pkg.add("CuArrays");'
     - julia --project -e 'using Pkg;
                           Pkg.instantiate();
                           Pkg.build();
                           Pkg.test(; coverage=true);'
 
 test:v1.0:
-  extends: .flux
-  variables:
-    CI_VERSION_TAG: 'v1.0'
-  only:
-    - staging
-    - trying
+   extends: .flux
+   variables:
+     CI_VERSION_TAG: 'v1.0'
 
 test:v1.1:
+   extends: .flux
+   variables:
+     CI_VERSION_TAG: 'v1.1'
+
+test:v1.2:
+   extends: .flux
+   variables:
+     CI_VERSION_TAG: 'v1.2'
+
+test:v1.3:
+   extends: .flux
+   variables:
+     CI_VERSION_TAG: 'v1.3'
+
+test:v1.0:
+   extends: .flux
+   variables:
+     CI_VERSION_TAG: 'v1.0'
+
+test:dev:
   extends: .flux
   variables:
-    CI_VERSION_TAG: 'v1.1'
-  only:
-    - staging
-    - trying
+    CI_VERSION_TAG: 'dev'
+
+  allow_failure: true
diff --git a/Manifest.toml b/Manifest.toml
index 4d825f17..87f5075f 100644
--- a/Manifest.toml
+++ b/Manifest.toml
@@ -149,9 +149,9 @@ uuid = "8ba89e20-285c-5b6f-9357-94700520ee1b"
 
 [[FFTW]]
 deps = ["AbstractFFTs", "BinaryProvider", "Conda", "Libdl", "LinearAlgebra", "Reexport", "Test"]
-git-tree-sha1 = "03f8776fbdae28c20c0d1d2ae4e090cd1dfcd247"
+git-tree-sha1 = "6c5b420da0b8c12098048561b8d58f81adea506f"
 uuid = "7a1cc6ca-52ef-59f5-83cd-3a7055c09341"
-version = "1.0.0"
+version = "1.0.1"
 
 [[FillArrays]]
 deps = ["LinearAlgebra", "Random", "SparseArrays"]
@@ -390,7 +390,7 @@ version = "0.8.3"
 
 [[Zygote]]
 deps = ["DiffRules", "FFTW", "FillArrays", "ForwardDiff", "IRTools", "InteractiveUtils", "LinearAlgebra", "MacroTools", "NNlib", "NaNMath", "Random", "Requires", "SpecialFunctions", "Statistics", "ZygoteRules"]
-git-tree-sha1 = "ce6d7142d665b1e4c71c678fa7db4da3bbc6743f"
+git-tree-sha1 = "38241b40ebd8748bcacad5e6c7ba3ab3cc7a15c9"
 repo-rev = "master"
 repo-url = "https://github.com/FluxML/Zygote.jl.git"
 uuid = "e88e6eb3-aa80-5325-afca-941959d7151f"
@@ -398,6 +398,8 @@ version = "0.3.4"
 
 [[ZygoteRules]]
 deps = ["MacroTools"]
-git-tree-sha1 = "def5f96ac2895fd9b48435f6b97020979ee0a4c6"
+git-tree-sha1 = "c4c29b30b8ff3be13d4244e78be7df2a42bc54d0"
+repo-rev = "master"
+repo-url = "https://github.com/FluxML/ZygoteRules.jl.git"
 uuid = "700de1a5-db45-46bc-99cf-38207098b444"
-version = "0.1.0"
+version = "0.2.0"
diff --git a/Project.toml b/Project.toml
index 7cd78984..5e357c59 100644
--- a/Project.toml
+++ b/Project.toml
@@ -23,13 +23,14 @@ StatsBase = "2913bbd2-ae8a-5f71-8c99-4fb6c76f3a91"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 ZipFile = "a5390f91-8eb1-5f08-bee0-b1d1ffed6cea"
 Zygote = "e88e6eb3-aa80-5325-afca-941959d7151f"
+ZygoteRules = "700de1a5-db45-46bc-99cf-38207098b444"
 
 [compat]
 CUDAapi = "1.1"
 CuArrays = "1.2"
 NNlib = "0.6"
 Zygote = "0.3"
-julia = "1.1"
+julia = "1"
 
 [extras]
 Documenter = "e30172f5-a6a5-5a46-863b-614d45cd2de4"
diff --git a/docs/src/gpu.md b/docs/src/gpu.md
index aed33f4e..bb13fdd1 100644
--- a/docs/src/gpu.md
+++ b/docs/src/gpu.md
@@ -25,16 +25,16 @@ loss(x, y) # ~ 3
 
 Note that we convert both the parameters (`W`, `b`) and the data set (`x`, `y`) to cuda arrays. Taking derivatives and training works exactly as before.
 
-If you define a structured model, like a `Dense` layer or `Chain`, you just need to convert the internal parameters. Flux provides `mapleaves`, which allows you to alter all parameters of a model at once.
+If you define a structured model, like a `Dense` layer or `Chain`, you just need to convert the internal parameters. Flux provides `fmap`, which allows you to alter all parameters of a model at once.
 
 ```julia
 d = Dense(10, 5, σ)
-d = mapleaves(cu, d)
+d = fmap(cu, d)
 d.W # Tracked CuArray
 d(cu(rand(10))) # CuArray output
 
 m = Chain(Dense(10, 5, σ), Dense(5, 2), softmax)
-m = mapleaves(cu, m)
+m = fmap(cu, m)
 d(cu(rand(10)))
 ```
 
diff --git a/docs/src/models/basics.md b/docs/src/models/basics.md
index ddd81992..d83fc462 100644
--- a/docs/src/models/basics.md
+++ b/docs/src/models/basics.md
@@ -215,7 +215,7 @@ m(5) # => 26
 Flux provides a set of helpers for custom layers, which you can enable by calling
 
 ```julia
-Flux.@treelike Affine
+Flux.@functor Affine
 ```
 
 This enables a useful extra set of functionality for our `Affine` layer, such as [collecting its parameters](../training/optimisers.md) or [moving it to the GPU](../gpu.md).
diff --git a/src/Flux.jl b/src/Flux.jl
index 9d1fbfc5..0b57f81d 100644
--- a/src/Flux.jl
+++ b/src/Flux.jl
@@ -6,12 +6,12 @@ using Base: tail
 using Zygote, MacroTools, Juno, Reexport, Statistics, Random
 using MacroTools: @forward
 @reexport using NNlib
-using Zygote: Params, @adjoint, gradient, forward
+using Zygote: Params, @adjoint, gradient, pullback
 export gradient
 
 export Chain, Dense, Maxout, RNN, LSTM, GRU, Conv, CrossCor, ConvTranspose, MaxPool, MeanPool,
        DepthwiseConv, Dropout, AlphaDropout, LayerNorm, BatchNorm, InstanceNorm, GroupNorm,
-       SkipConnection, params, mapleaves, cpu, gpu, f32, f64
+       SkipConnection, params, fmap, cpu, gpu, f32, f64
 
 include("optimise/Optimise.jl")
 using .Optimise
@@ -35,7 +35,7 @@ end
 
 include("utils.jl")
 include("onehot.jl")
-include("treelike.jl")
+include("functor.jl")
 
 include("layers/stateless.jl")
 include("layers/basic.jl")
diff --git a/src/functor.jl b/src/functor.jl
new file mode 100644
index 00000000..73483ab9
--- /dev/null
+++ b/src/functor.jl
@@ -0,0 +1,91 @@
+import Adapt: adapt, adapt_storage
+using Zygote: IdSet
+
+functor(x) = (), _ -> x
+
+functor(x::Tuple) = x, y -> y
+functor(x::NamedTuple) = x, y -> y
+
+functor(x::AbstractArray) = x, y -> y
+functor(x::AbstractArray{<:Number}) = (), _ -> x
+
+function makefunctor(m::Module, T, fs = fieldnames(T))
+  @eval m begin
+    Flux.functor(x::$T) = ($([:($f=x.$f) for f in fs]...),), y -> $T(y...)
+  end
+end
+
+function functorm(T, fs = nothing)
+  fs == nothing || isexpr(fs, :tuple) || error("@functor T (a, b)")
+  fs = fs == nothing ? [] : [:($(map(QuoteNode, fs.args)...),)]
+  :(makefunctor(@__MODULE__, $(esc(T)), $(fs...)))
+end
+
+macro functor(args...)
+  functorm(args...)
+end
+
+isleaf(x) = functor(x)[1] === ()
+
+function fmap1(f, x)
+  func, re = functor(x)
+  re(map(f, func))
+end
+
+function fmap(f, x; cache = IdDict())
+  haskey(cache, x) && return cache[x]
+  cache[x] = isleaf(x) ? f(x) : fmap1(x -> fmap(f, x, cache = cache), x)
+end
+
+trainable(m) = functor(m)[1]
+
+params!(p::Params, x::AbstractArray{<:Real}, seen = IdSet()) = push!(p, x)
+
+function params!(p::Params, x, seen = IdSet())
+  x in seen && return
+  push!(seen, x)
+  for child in trainable(x)
+    params!(p, child, seen)
+  end
+end
+
+function params(m...)
+  ps = Params()
+  params!(ps, m)
+  return ps
+end
+
+# Deprecated stuff
+macro treelike(args...)
+  functorm(args...)
+end
+mapleaves(f, x) = fmap(f, x)
+
+function loadparams!(m, xs)
+  for (p, x) in zip(params(m), xs)
+    size(p) == size(x) ||
+      error("Expected param size $(size(p)), got $(size(x))")
+    copyto!(p, x)
+  end
+end
+
+# CPU/GPU movement conveniences
+
+cpu(m) = fmap(x -> adapt(Array, x), m)
+
+const gpu_adaptor = if has_cuarrays()
+  CuArrays.cu
+else
+  identity
+end
+
+gpu(x) = fmap(gpu_adaptor, x)
+
+# Precision
+
+adapt_storage(T::Type{<:Real}, xs::AbstractArray{<:Real}) = convert.(T, xs)
+
+paramtype(T::Type{<:Real}, m) = fmap(x -> adapt(T, x), m)
+
+f32(m) = paramtype(Float32, m)
+f64(m) = paramtype(Float64, m)
diff --git a/src/layers/basic.jl b/src/layers/basic.jl
index 0cebead1..f42a9619 100644
--- a/src/layers/basic.jl
+++ b/src/layers/basic.jl
@@ -24,8 +24,7 @@ end
 @forward Chain.layers Base.getindex, Base.length, Base.first, Base.last,
   Base.iterate, Base.lastindex
 
-children(c::Chain) = c.layers
-mapchildren(f, c::Chain) = Chain(f.(c.layers)...)
+functor(c::Chain) = c.layers, ls -> Chain(ls...)
 
 applychain(::Tuple{}, x) = x
 applychain(fs::Tuple, x) = applychain(tail(fs), first(fs)(x))
@@ -92,7 +91,7 @@ function Dense(in::Integer, out::Integer, σ = identity;
   return Dense(initW(out, in), initb(out), σ)
 end
 
-@treelike Dense
+@functor Dense
 
 function (a::Dense)(x::AbstractArray)
   W, b, σ = a.W, a.b, a.σ
@@ -131,7 +130,7 @@ end
 Diagonal(in::Integer; initα = ones, initβ = zeros) =
   Diagonal(initα(in), initβ(in))
 
-@treelike Diagonal
+@functor Diagonal
 
 function (a::Diagonal)(x)
   α, β = a.α, a.β
@@ -184,24 +183,29 @@ function Maxout(f, n_alts)
   return Maxout(over)
 end
 
-@treelike Maxout
+@functor Maxout
 
 function (mo::Maxout)(input::AbstractArray)
     mapreduce(f -> f(input), (acc, out) -> max.(acc, out), mo.over)
 end
 
 """
-    SkipConnection(layers...)
+    SkipConnection(layers, connection)
 
-Creates a Skip Connection, which constitutes of a layer or Chain of consecutive layers
-and a shortcut connection linking the input to the block to the
-output through a user-supplied callable.
+Creates a Skip Connection, of a layer or `Chain` of consecutive layers
+plus a shortcut connection. The connection function will combine the result of the layers
+with the original input, to give the final output.
 
-`SkipConnection` requires the output dimension to be the same as the input.
+The simplest 'ResNet'-type connection is just `SkipConnection(layer, +)`,
+and requires the output of the layers to be the same shape as the input.
+Here is a more complicated example:
+```
+m = Conv((3,3), 4=>7, pad=(1,1))
+x = ones(5,5,4,10);
+size(m(x)) == (5, 5, 7, 10)
 
-A 'ResNet'-type skip-connection with identity shortcut would simply be
-```julia
-    SkipConnection(layer, (a,b) -> a + b)
+sm = SkipConnection(m, (mx, x) -> cat(mx, x, dims=3))
+size(sm(x)) == (5, 5, 11, 10)
 ```
 """
 struct SkipConnection
@@ -209,15 +213,12 @@ struct SkipConnection
   connection  #user can pass arbitrary connections here, such as (a,b) -> a + b
 end
 
-@treelike SkipConnection
+@functor SkipConnection
 
 function (skip::SkipConnection)(input)
-  #We apply the layers to the input and return the result of the application of the layers and the original input
   skip.connection(skip.layers(input), input)
 end
 
 function Base.show(io::IO, b::SkipConnection)
-  print(io, "SkipConnection(")
-  join(io, b.layers, ", ")
-  print(io, ")")
+  print(io, "SkipConnection(", b.layers, ", ", b.connection, ")")
 end
diff --git a/src/layers/conv.jl b/src/layers/conv.jl
index 4361a389..519f129f 100644
--- a/src/layers/conv.jl
+++ b/src/layers/conv.jl
@@ -45,7 +45,7 @@ Conv(k::NTuple{N,Integer}, ch::Pair{<:Integer,<:Integer}, σ = identity;
   Conv(init(k..., ch...), zeros(ch[2]), σ,
        stride = stride, pad = pad, dilation = dilation)
 
-@treelike Conv
+@functor Conv
 
 function (c::Conv)(x::AbstractArray)
   # TODO: breaks gpu broadcast :(
@@ -102,7 +102,7 @@ ConvTranspose(k::NTuple{N,Integer}, ch::Pair{<:Integer,<:Integer}, σ = identity
 ConvTranspose(init(k..., reverse(ch)...), zeros(ch[2]), σ,
               stride = stride, pad = pad, dilation = dilation)
 
-@treelike ConvTranspose
+@functor ConvTranspose
 
 function conv_transpose_dims(c::ConvTranspose, x::AbstractArray)
     # Calculate size of "input", from ∇conv_data()'s perspective...
@@ -180,7 +180,7 @@ function DepthwiseConv(k::NTuple{N,Integer}, ch::Pair{<:Integer,<:Integer}, σ =
   )
 end
 
-@treelike DepthwiseConv
+@functor DepthwiseConv
 
 function (c::DepthwiseConv)(x)
   σ, b = c.σ, reshape(c.bias, map(_->1, c.stride)..., :, 1)
@@ -244,7 +244,7 @@ CrossCor(k::NTuple{N,Integer}, ch::Pair{<:Integer,<:Integer}, σ = identity;
   CrossCor(init(k..., ch...), zeros(ch[2]), σ,
        stride = stride, pad = pad, dilation = dilation)
 
-@treelike CrossCor
+@functor CrossCor
 
 function crosscor(x, w, ddims::DenseConvDims)
   ddims = DenseConvDims(ddims, F=true)
diff --git a/src/layers/normalise.jl b/src/layers/normalise.jl
index 61a62adf..b421d3e7 100644
--- a/src/layers/normalise.jl
+++ b/src/layers/normalise.jl
@@ -82,7 +82,7 @@ end
 LayerNorm(h::Integer) =
   LayerNorm(Diagonal(h))
 
-@treelike LayerNorm
+@functor LayerNorm
 
 (a::LayerNorm)(x) = a.diag(normalise(x))
 
@@ -134,6 +134,8 @@ BatchNorm(chs::Integer, λ = identity;
   BatchNorm(λ, initβ(chs), initγ(chs),
             zeros(chs), ones(chs), ϵ, momentum)
 
+trainable(bn::BatchNorm) = (bn.β, bn.γ)
+
 function (BN::BatchNorm)(x)
   size(x, ndims(x)-1) == length(BN.β) ||
     error("BatchNorm expected $(length(BN.β)) channels, got $(size(x, ndims(x)-1))")
@@ -166,11 +168,7 @@ function (BN::BatchNorm)(x)
   end
 end
 
-children(BN::BatchNorm) =
-  (BN.λ, BN.β, BN.γ, BN.μ, BN.σ², BN.ϵ, BN.momentum)
-
-mapchildren(f, BN::BatchNorm) =  # e.g. mapchildren(cu, BN)
-  BatchNorm(BN.λ, f(BN.β), f(BN.γ), f(BN.μ), f(BN.σ²), BN.ϵ, BN.momentum)
+@functor BatchNorm
 
 function Base.show(io::IO, l::BatchNorm)
   print(io, "BatchNorm($(join(size(l.β), ", "))")
@@ -224,6 +222,8 @@ InstanceNorm(chs::Integer, λ = identity;
   InstanceNorm(λ, initβ(chs), initγ(chs),
             zeros(chs), ones(chs), ϵ, momentum)
 
+trainable(in::InstanceNorm) = (in.β, in.γ)
+
 function (in::InstanceNorm)(x)
   size(x, ndims(x)-1) == length(in.β) ||
     error("InstanceNorm expected $(length(in.β)) channels, got $(size(x, ndims(x)-1))")
@@ -261,11 +261,7 @@ function (in::InstanceNorm)(x)
   end
 end
 
-children(in::InstanceNorm) =
-  (in.λ, in.β, in.γ, in.μ, in.σ², in.ϵ, in.momentum)
-
-mapchildren(f, in::InstanceNorm) =  # e.g. mapchildren(cu, in)
-  InstanceNorm(in.λ, f(in.β), f(in.γ), f(in.μ), f(in.σ²), in.ϵ, in.momentum)
+@functor InstanceNorm
 
 function Base.show(io::IO, l::InstanceNorm)
   print(io, "InstanceNorm($(join(size(l.β), ", "))")
@@ -311,6 +307,8 @@ GroupNorm(chs::Integer, G::Integer, λ = identity;
   GroupNorm(G, λ, initβ(chs), initγ(chs),
             zeros(G,1), ones(G,1), ϵ, momentum)
 
+trainable(gn::GroupNorm) = (gn.β, gn.γ)
+
 function(gn::GroupNorm)(x)
   size(x,ndims(x)-1) == length(gn.β) || error("Group Norm expected $(length(gn.β)) channels, but got $(size(x,ndims(x)-1)) channels")
   ndims(x) > 2 || error("Need to pass at least 3 channels for Group Norm to work")
@@ -360,11 +358,7 @@ function(gn::GroupNorm)(x)
   end
 end
 
-children(gn::GroupNorm) =
-  (gn.λ, gn.β, gn.γ, gn.μ, gn.σ², gn.ϵ, gn.momentum)
-
-mapchildren(f, gn::GroupNorm) =  # e.g. mapchildren(cu, BN)
-  GroupNorm(gn.G,gn.λ, f(gn.β), f(gn.γ), f(gn.μ), f(gn.σ²), gn.ϵ, gn.momentum)
+@functor GroupNorm
 
 function Base.show(io::IO, l::GroupNorm)
   print(io, "GroupNorm($(join(size(l.β), ", "))")
diff --git a/src/layers/recurrent.jl b/src/layers/recurrent.jl
index b5eea4a4..f2344af8 100644
--- a/src/layers/recurrent.jl
+++ b/src/layers/recurrent.jl
@@ -38,7 +38,7 @@ function (m::Recur)(xs...)
   return y
 end
 
-@treelike Recur cell, init
+@functor Recur cell, init
 
 Base.show(io::IO, m::Recur) = print(io, "Recur(", m.cell, ")")
 
@@ -52,7 +52,8 @@ Assuming you have a `Recur` layer `rnn`, this is roughly equivalent to
 
     rnn.state = hidden(rnn.cell)
 """
-reset!(m) = prefor(x -> x isa Recur && (x.state = x.init), m)
+reset!(m::Recur) = (m.state = m.init)
+reset!(m) = foreach(reset!, functor(m)[1])
 
 flip(f, xs) = reverse(f.(reverse(xs)))
 
@@ -79,7 +80,7 @@ end
 
 hidden(m::RNNCell) = m.h
 
-@treelike RNNCell
+@functor RNNCell
 
 function Base.show(io::IO, l::RNNCell)
   print(io, "RNNCell(", size(l.Wi, 2), ", ", size(l.Wi, 1))
@@ -127,7 +128,7 @@ end
 
 hidden(m::LSTMCell) = (m.h, m.c)
 
-@treelike LSTMCell
+@functor LSTMCell
 
 Base.show(io::IO, l::LSTMCell) =
   print(io, "LSTMCell(", size(l.Wi, 2), ", ", size(l.Wi, 1)÷4, ")")
@@ -168,7 +169,7 @@ end
 
 hidden(m::GRUCell) = m.h
 
-@treelike GRUCell
+@functor GRUCell
 
 Base.show(io::IO, l::GRUCell) =
   print(io, "GRUCell(", size(l.Wi, 2), ", ", size(l.Wi, 1)÷3, ")")
diff --git a/src/treelike.jl b/src/treelike.jl
deleted file mode 100644
index 42b10f23..00000000
--- a/src/treelike.jl
+++ /dev/null
@@ -1,86 +0,0 @@
-import Adapt: adapt, adapt_storage
-import Zygote: IdSet
-
-children(x) = ()
-mapchildren(f, x) = x
-
-children(x::Tuple) = x
-children(x::NamedTuple) = x
-mapchildren(f, x::Tuple) = map(f, x)
-mapchildren(f, x::NamedTuple) = map(f, x)
-
-function treelike(m::Module, T, fs = fieldnames(T))
-  @eval m begin
-    Flux.children(x::$T) = ($([:(x.$f) for f in fs]...),)
-    Flux.mapchildren(f, x::$T) = $T(f.($children(x))...)
-  end
-end
-
-macro treelike(T, fs = nothing)
-  fs == nothing || isexpr(fs, :tuple) || error("@treelike T (a, b)")
-  fs = fs == nothing ? [] : [:($(map(QuoteNode, fs.args)...),)]
-  :(treelike(@__MODULE__, $(esc(T)), $(fs...)))
-end
-
-isleaf(x) = isempty(children(x))
-
-function mapleaves(f, x; cache = IdDict())
-  haskey(cache, x) && return cache[x]
-  cache[x] = isleaf(x) ? f(x) : mapchildren(x -> mapleaves(f, x, cache = cache), x)
-end
-
-function prefor(f, x; seen = IdSet())
-  x ∈ seen && return
-  push!(seen, x)
-  f(x)
-  foreach(x -> prefor(f, x, seen = seen), children(x))
-  return
-end
-
-function params(m)
-  ps = Params()
-  prefor(p ->
-    p isa AbstractArray{<:Real} &&
-      !any(p′ -> p′ === p, ps) && push!(ps, p),
-    m)
-  return ps
-end
-
-params(m...) = params(m)
-
-function loadparams!(m, xs)
-  for (p, x) in zip(params(m), xs)
-    size(p) == size(x) ||
-      error("Expected param size $(size(p)), got $(size(x))")
-    copyto!(p, x)
-  end
-end
-
-# CPU/GPU movement conveniences
-
-cpu(m) = mapleaves(x -> adapt(Array, x), m)
-
-const gpu_adaptor = if has_cuarrays()
-  CuArrays.cu
-else
-  identity
-end
-
-gpu(x) = mapleaves(gpu_adaptor, x)
-
-# Precision
-
-adapt_storage(T::Type{<:Real}, xs::AbstractArray{<:Real}) = convert.(T, xs)
-
-paramtype(T::Type{<:Real}, m) = mapleaves(x -> adapt(T, x), m)
-
-f32(m) = paramtype(Float32, m)
-f64(m) = paramtype(Float64, m)
-
-# General parameter map
-
-function mapparams(f, m)
-  mapleaves(m) do x
-    x isa Union{AbstractArray,Number} ? f(x) : x
-  end
-end
diff --git a/test/cuda/cuda.jl b/test/cuda/cuda.jl
index 20399ef7..59bc7f50 100644
--- a/test/cuda/cuda.jl
+++ b/test/cuda/cuda.jl
@@ -1,4 +1,5 @@
-using Flux, CuArrays, Test
+using Flux, Test
+using Flux.CuArrays
 using Flux: gpu
 
 @info "Testing GPU Support"
diff --git a/test/cuda/cudnn.jl b/test/cuda/cudnn.jl
index a7fc244e..881e0b39 100644
--- a/test/cuda/cudnn.jl
+++ b/test/cuda/cudnn.jl
@@ -1,5 +1,5 @@
 using Flux, CuArrays, Test
-using Flux: forward
+using Flux: pullback
 
 @testset "CUDNN BatchNorm" begin
     @testset "4D Input" begin
@@ -8,8 +8,8 @@ using Flux: forward
         cx = gpu(x)
         cm = gpu(m)
 
-        y, back = forward((m, x) -> m(x), m, x)
-        cy, cback = forward((m, x) -> m(x), cm, cx)
+        y, back = pullback((m, x) -> m(x), m, x)
+        cy, cback = pullback((m, x) -> m(x), cm, cx)
 
         @test cpu(cy) ≈ y
 
@@ -28,8 +28,8 @@ using Flux: forward
         cx = gpu(x)
         cm = gpu(m)
 
-        y, back = forward((m, x) -> m(x), m, x)
-        cy, cback = forward((m, x) -> m(x), cm, cx)
+        y, back = pullback((m, x) -> m(x), m, x)
+        cy, cback = pullback((m, x) -> m(x), cm, cx)
 
         @test cpu(cy) ≈ y
 
diff --git a/test/cuda/curnn.jl b/test/cuda/curnn.jl
index e417ea58..7753837a 100644
--- a/test/cuda/curnn.jl
+++ b/test/cuda/curnn.jl
@@ -1,5 +1,5 @@
 using Flux, CuArrays, Test
-using Flux: forward
+using Flux: pullback
 
 @testset for R in [RNN, GRU, LSTM]
   m = R(10, 5) |> gpu
@@ -13,7 +13,7 @@ end
 @testset "RNN" begin
   @testset for R in [RNN, GRU, LSTM], batch_size in (1, 5)
     rnn = R(10, 5)
-    curnn = mapleaves(gpu, rnn)
+    curnn = fmap(gpu, rnn)
 
     Flux.reset!(rnn)
     Flux.reset!(curnn)
@@ -22,8 +22,8 @@ end
       rand(10, batch_size)
     cux = gpu(x)
 
-    y, back = forward((r, x) -> r(x), rnn, x)
-    cuy, cuback = forward((r, x) -> r(x), curnn, cux)
+    y, back = pullback((r, x) -> r(x), rnn, x)
+    cuy, cuback = pullback((r, x) -> r(x), curnn, cux)
 
     @test y ≈ collect(cuy)
     @test haskey(Flux.CUDA.descs, curnn.cell)
diff --git a/test/layers/normalisation.jl b/test/layers/normalisation.jl
index cda0cc59..22a5d283 100644
--- a/test/layers/normalisation.jl
+++ b/test/layers/normalisation.jl
@@ -1,7 +1,7 @@
 using Flux, Test, Statistics
-using Zygote: forward
+using Zygote: pullback
 
-trainmode(f, x...) = forward(f, x...)[1]
+trainmode(f, x...) = pullback(f, x...)[1]
 trainmode(f) = (x...) -> trainmode(f, x...)
 
 @testset "Dropout" begin
@@ -42,6 +42,8 @@ end
   let m = BatchNorm(2), x = [1.0 3.0 5.0;
                              2.0 4.0 6.0]
 
+    @test length(params(m)) == 2
+
     @test m.β == [0, 0]  # initβ(2)
     @test m.γ == [1, 1]  # initγ(2)
     # initial m.σ is 1
@@ -109,7 +111,9 @@ end
   expand_inst = (x, as) -> reshape(repeat(x, outer=[1, as[length(as)]]), as...)
   # begin tests
   let m = InstanceNorm(2), sizes = (3, 2, 2),
-      x = reshape(collect(1:prod(sizes)), sizes)
+        x = reshape(collect(1:prod(sizes)), sizes)
+
+      @test length(params(m)) == 2
       x = Float64.(x)
       @test m.β == [0, 0]  # initβ(2)
       @test m.γ == [1, 1]  # initγ(2)
@@ -192,7 +196,9 @@ end
   squeeze(x) = dropdims(x, dims = tuple(findall(size(x) .== 1)...)) # To remove all singular dimensions
 
   let m = GroupNorm(4,2), sizes = (3,4,2),
-      x = reshape(collect(1:prod(sizes)), sizes)
+        x = reshape(collect(1:prod(sizes)), sizes)
+
+      @test length(params(m)) == 2
       x = Float64.(x)
       @test m.β == [0, 0, 0, 0]  # initβ(32)
       @test m.γ == [1, 1, 1, 1]  # initγ(32)
diff --git a/test/layers/stateless.jl b/test/layers/stateless.jl
index b853fc19..9e01af07 100644
--- a/test/layers/stateless.jl
+++ b/test/layers/stateless.jl
@@ -55,7 +55,7 @@ const ϵ = 1e-7
       y = rand(T, 2)
       ŷ = rand(T, 2)
       for f in (mse, crossentropy, logitcrossentropy)
-        fwd, back = Flux.forward(f, ŷ, y)
+        fwd, back = Flux.pullback(f, ŷ, y)
         @test fwd isa T
         @test eltype(back(one(T))[1]) == T
       end
diff --git a/test/utils.jl b/test/utils.jl
index 3a840261..18a57139 100644
--- a/test/utils.jl
+++ b/test/utils.jl
@@ -83,7 +83,6 @@ end
 
   # Self-referential array. Just want params, no stack overflow pls.
   r = Any[nothing,m]
-  Flux.children(a::Vector{Any}) = Tuple(a)
   r[1] = r
   @test size.(params(r)) == [(5, 10), (5, 5), (5,), (5,)]
 end