diff --git a/src/compiler/code.jl b/src/compiler/code.jl
index 27a35c63..e44e6563 100644
--- a/src/compiler/code.jl
+++ b/src/compiler/code.jl
@@ -1,8 +1,8 @@
-import Flow: mapconst
+import Flow: mapconst, cse
 
 function process_func(ex, params)
   @capture(shortdef(ex), (args__,) -> body_)
-  body = il(graphm(body))
+  body = Flow.il(graphm(body))
   body = mapconst(x -> x in params ? :(self.$x) : x, body)
   return args, body
 end
@@ -30,7 +30,7 @@ function build_backward(body, x, params)
     k = symbol("Δ", param)
     ksym = Expr(:quote, k)
     ex = Δs[:(self.$param)]
-    thread!(back, @vertex(setfield!(:self, ksym, :(self.$k) + ex)))
+    thread!(back, @dvertex(setfield!(:self, ksym, :(self.$k) + ex)))
   end
   ex = Δs[x]
   thread!(back, @flow(tuple($ex)))
diff --git a/src/compiler/diff.jl b/src/compiler/diff.jl
index efab7943..0cf4bf9b 100644
--- a/src/compiler/diff.jl
+++ b/src/compiler/diff.jl
@@ -1,10 +1,3 @@
-import Flow: isconstant, il, dl, cse, prewalk, graphm, syntax, @vertex
-
-vertex(a...) = IVertex{Any}(a...)
-vertex(v::Vertex) = convert(IVertex{Any}, v)
-constant(x) = vertex(Flow.Constant(x))
-constant(x::Vertex) = vertex(x)
-
 addΔ(a, b) = vertex(:+, a, b)
 
 # Special case a couple of operators to clean up output code
@@ -18,11 +11,11 @@ function ∇v(v::Vertex, Δ)
   map(i -> @flow(getindex($Δ, $i)), 1:Flow.nin(v))
 end
 
-function invert(v::IVertex, Δ = constant(:Δ), out = d())
+function invert(v::IVertex, Δ = :Δ, out = d())
   @assert !iscyclic(v)
   if isconstant(v)
     @assert !haskey(out, value(v))
-    out[value(v).value] = il(Δ)
+    out[value(v).value] = constant(Δ)
   else
     Δ′s = ∇v(v, Δ)
     for (v′, Δ′) in zip(inputs(v), Δ′s)