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