diff --git a/base/essentials.jl b/base/essentials.jl
index 2093c792dd9b4..61e9b1b25800d 100644
--- a/base/essentials.jl
+++ b/base/essentials.jl
@@ -386,8 +386,10 @@ function isvatuple(@nospecialize(t))
     return false
 end
 
-unwrapva(t::Core.TypeofVararg) = isdefined(t, :T) ? t.T : Any
-unwrapva(@nospecialize(t)) = t
+function unwrapva(@nospecialize(t))
+    isa(t, Core.TypeofVararg) || return t
+    return isdefined(t, :T) ? t.T : Any
+end
 
 function unconstrain_vararg_length(va::Core.TypeofVararg)
     # construct a new Vararg type where its length is unconstrained,
diff --git a/base/tuple.jl b/base/tuple.jl
index 962a26d8fa789..219315e77944d 100644
--- a/base/tuple.jl
+++ b/base/tuple.jl
@@ -213,13 +213,12 @@ function _tuple_unique_fieldtypes(@nospecialize t)
     t´ = unwrap_unionall(t)
     # Given t = Tuple{Vararg{S}} where S<:Real, the various
     # unwrapping/wrapping/va-handling here will return Real
-    if t isa Union
+    if t´ isa Union
         union!(types, _tuple_unique_fieldtypes(rewrap_unionall(t´.a, t)))
         union!(types, _tuple_unique_fieldtypes(rewrap_unionall(t´.b, t)))
     else
-        r = Union{}
         for ti in (t´::DataType).parameters
-            r = push!(types, rewrap_unionall(unwrapva(ti), t))
+            push!(types, rewrap_unionall(unwrapva(ti), t))
         end
     end
     return Core.svec(types...)