diff --git a/src/layers/recurrent.jl b/src/layers/recurrent.jl
index 969a777e..15a590b7 100644
--- a/src/layers/recurrent.jl
+++ b/src/layers/recurrent.jl
@@ -84,7 +84,7 @@ end
 RNNCell(in::Integer, out::Integer, σ = tanh;
         init = glorot_uniform) =
   RNNCell(σ, param(init(out, in)), param(init(out, out)),
-          param(zero(out)), param(initn(out)))
+          param(fill(0.0,out)), param(initn(out)))
 
 function (m::RNNCell)(h, x)
   σ, Wi, Wh, b = m.σ, m.Wi, m.Wh, m.b
diff --git a/src/tracker/array.jl b/src/tracker/array.jl
index 7c23288f..818e5e73 100644
--- a/src/tracker/array.jl
+++ b/src/tracker/array.jl
@@ -205,16 +205,16 @@ Base.kron(a::AbstractMatrix, b::TrackedMatrix) = _kron(a, b)
 
 # Reductions
 
-Base.sum(xs::TrackedArray; dims) = track(sum, xs, dims)
-Base.sum(xs::TrackedArray) = track(sum, xs)
+Base.sum(xs::TrackedArray; dims = :) = track(sum, xs, dims = dims)
+# Base.sum(xs::TrackedArray) = track(sum, xs)
 Base.sum(f::Union{Function,Type},xs::TrackedArray) = sum(f.(xs))
 
-@grad sum(xs, dims::Int) = sum(data(xs), dims = dims),
-  Δ -> (zero(xs) .+ Δ, nothing)
-@grad sum(xs, dims) = sum(data(xs), dims = dims),
-  Δ -> (zero(xs) .+ Δ, map(_->nothing,dims)...)
-@grad sum(xs) = sum(data(xs)),
-  Δ -> (zero(xs) .+ Δ,)
+# @grad sum(xs, dims::Int) = sum(data(xs), dims = dims),
+  # Δ -> (zero(xs) .+ Δ, nothing)
+@grad sum(xs; dims = :) = sum(data(xs), dims = dims),
+  Δ -> (zero(xs) .+ Δ, )
+# @grad sum(xs) = sum(data(xs)),
+  # Δ -> (zero(xs) .+ Δ,)
 
 Base.prod(xs::TrackedArray, dim) = track(prod, xs, dim)
 Base.prod(xs::TrackedArray) = track(prod, xs)