diff --git a/base/iterators.jl b/base/iterators.jl
index b329a6c6f9eff..cbb9b0a8e7996 100644
--- a/base/iterators.jl
+++ b/base/iterators.jl
@@ -1089,10 +1089,9 @@ end
 
 @inline peek(s::Stateful, sentinel=nothing) = s.nextvalstate !== nothing ? s.nextvalstate[1] : sentinel
 @inline iterate(s::Stateful, state=nothing) = s.nextvalstate === nothing ? nothing : (popfirst!(s), nothing)
-IteratorSize(::Type{Stateful{VS,T}} where VS) where {T} =
-    isa(IteratorSize(T), SizeUnknown) ? SizeUnknown() : HasLength()
+IteratorSize(::Type{Stateful{T,VS}}) where {T,VS} = IteratorSize(T)
 eltype(::Type{Stateful{T, VS}} where VS) where {T} = eltype(T)
-IteratorEltype(::Type{Stateful{VS,T}} where VS) where {T} = IteratorEltype(T)
+IteratorEltype(::Type{Stateful{T,VS}}) where {T,VS} = IteratorEltype(T)
 length(s::Stateful) = length(s.itr) - s.taken
 
 end