diff --git a/src/flatten.jl b/src/flatten.jl
index 3d66fc2..08c8f23 100644
--- a/src/flatten.jl
+++ b/src/flatten.jl
@@ -84,7 +84,7 @@ function flatten(::Type{T}, x::Tuple) where {T<:Real}
     l1 = length(vec1)
     l2 = length(vec2)
     function unflatten_to_Tuple(v::Vector{T})
-        return (back1(v[1:l1]), back2(v[l1+1:l1+l2])...)
+        return (back1(v[1:l1]), back2(v[(l1 + 1):(l1 + l2)])...)
     end
     return vcat(vec1, vec2), unflatten_to_Tuple
 end