diff --git a/src/backend/mxnet/graph.jl b/src/backend/mxnet/graph.jl
index fe9ccd07..313519a0 100644
--- a/src/backend/mxnet/graph.jl
+++ b/src/backend/mxnet/graph.jl
@@ -46,6 +46,15 @@ graph(::typeof(map), f, xss::Tuple...) = map(f, xss...)
 
 graph(::Input, x) = x
 
+struct AlterParam
+  param
+  load
+  store
+end
+
+Base.size(p::AlterParam) = size(p.load(p.param.x))
+Base.copy!(xs, p::AlterParam) = copy!(xs, p.load(p.param.x))
+
 graph(ctx::Context, d::Affine, x) =
   !ctx[:feedforward] ? invoke(graph, Tuple{Context, Any, typeof(x)}, ctx, d, x) :
     register(ctx,
@@ -74,19 +83,16 @@ end
 
 register(ctx::Context, node) = node
 
-function var(ctx::Context, p)
+function var(ctx::Context, p::Union{Flux.Param{<:AArray},AArray,AlterParam})
   id = gensym()
   ctx[:params][id] = p
   return mx.Variable(id)
 end
 
-graph{T<:AArray}(ctx::Context, p::Constant{Flux.Param{T}}) = var(ctx, p.value)
-
-graph{T<:AArray}(ctx::Context, p::Constant{T}) = var(ctx, p.value)
-
-graph(ctx::Context, p::Constant) = p.value
+var(ctx::Context, x) = x
 
 function graph(ctx::Context, model, args...)
+  args = var.(ctx, args)
   g = Flux.graph(model)
   g == nothing && return register(ctx, @icatch ctx graph(model, args...))
   DataFlow.iscyclic(g) && error("This model has a cycle; try unrolling it first.")
@@ -96,7 +102,7 @@ end
 graph′(ctx::Context, args...) = @icatch ctx graph(ctx, args...)
 
 function tograph(model, args...; feedforward = false)
-  ctx = Context(mux(iline, ilambda, iargs, ituple, graph′),
+  ctx = Context(mux(iline, iconst, ilambda, iargs, ituple, graph′),
                 params = Dict(), stacks = Dict(),
                 feedforward = feedforward)
   out = @ithrow graph(ctx, model, mapt(mx.Variable, args)...)
diff --git a/src/backend/mxnet/model.jl b/src/backend/mxnet/model.jl
index 507c01c2..7d3c7895 100644
--- a/src/backend/mxnet/model.jl
+++ b/src/backend/mxnet/model.jl
@@ -1,14 +1,5 @@
 using Flux: collectt, shapecheckt
 
-struct AlterParam
-  param
-  load
-  store
-end
-
-Base.size(p::AlterParam) = size(p.load(p.param.x))
-Base.copy!(xs, p::AlterParam) = copy!(xs, p.load(p.param.x))
-
 function copyargs!(as, bs)
   for id in intersect(keys(as), keys(bs))
     copy!(as[id], bs[id])