From af8fdcc7af9252f36ce449e3238c818f4b83d504 Mon Sep 17 00:00:00 2001
From: Mike Innes <mike.j.innes@gmail.com>
Date: Mon, 28 Jan 2019 10:54:44 +0000
Subject: [PATCH] fix #573

---
 src/tracker/lib/real.jl | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/tracker/lib/real.jl b/src/tracker/lib/real.jl
index 0d8b3f43..be6f62f0 100644
--- a/src/tracker/lib/real.jl
+++ b/src/tracker/lib/real.jl
@@ -106,6 +106,7 @@ import Base:^
 using ForwardDiff: Dual
 
 (T::Type{<:Real})(x::Dual) = Dual(T(x.value), map(T, x.partials.values))
+(Dual{T,V,N})(x::Dual) where {T,V,N} = invoke(Dual{T,V,N}, Tuple{Number}, x)
 
 # Tuples