diff --git a/src/optics.jl b/src/optics.jl
index ef02e4c2..aa443a49 100644
--- a/src/optics.jl
+++ b/src/optics.jl
@@ -129,24 +129,14 @@ end
 struct Changed end
 struct Unchanged end
 
-struct ConstructIfChanged{C}
-    constructor::C
-end
-
-# TODO what do we call these things?
-struct Construct end
-_constructor(::Construct, ::Type{T}) where T = constructorof(T)
-
 struct MaybeConstruct end
-function _constructor(::MaybeConstruct, ::Type{T}) where T 
-    ConstructIfChanged(constructorof(T))
-end
+_constructor(::MaybeConstruct, ::Type{T}) where T = constructorof(T)
 
 struct List end
 _constructor(::List, ::Type) = tuple
 
-struct Splat end
-_constructor(::Splat, ::Type) = _splat_all
+struct Skip end
+_constructor(::Skip, ::Type) = _splat_all
 
 _splat_all(args...) = _splat_all(args)  
 @generated function _splat_all(args::A) where A<:Tuple  
@@ -297,7 +287,7 @@ function mapobject(f, obj::O, ::Properties, handler, itr::Nothing) where O
     # TODO move this helper elsewhere?
     pnames = propertynames(obj)
     if isempty(pnames)
-        return obj
+        return _maybeskip(handler, obj)
     else
         new_props = map(pnames) do p
             f(getproperty(obj, p))
@@ -344,56 +334,69 @@ $EXPERIMENTAL
 """
 struct Fields <: ObjectMap end
 
-@generated function mapobject(f, obj::O, ::Fields, handler::H=Construct(), itr::I=nothing) where {O,H,I}
+@generated function mapobject(f, obj::O, ::Fields, handler::H, itr::Nothing) where {O,H,I}
     # TODO: This is how Flatten.jl works, but it's not really 
     # correct use of ConstructionBase as it assumers properties=fields
     fnames = fieldnames(O)
     ctr = _constructor(H(), O)
     if isempty(fnames)
-        :(return _maybeitr(obj, itr))
+        :(return _maybeskip(handler, obj))
     else
         prop_args = map(fn -> :(getfield(obj, $(QuoteNode(fn)))), fnames)
         prop_exp = Expr(:tuple, prop_args...)
-        if I === Nothing
-            new_prop_exp = Expr(:tuple, map(pa -> :(f($pa)), prop_args)...)
-        else 
-            ### Unrolled iterating function appliation (it will compile away) ####
-            # Each function call also updates the iterator value in local scoope with 
-            # the return value from the function. But it only actually inserts the 
-            # value into the parent tuple.
-            val_exps = map(prop_args) do pa
-                :((val, itr) = f($pa, itr); val)
-            end
-            new_prop_exp = Expr(:tuple, val_exps...)
+        new_prop_exp = Expr(:tuple, map(pa -> :(f($pa)), prop_args)...)
+        quote 
+            props = $prop_exp
+            new_props = $new_prop_exp
+            return $ctr(new_props...)
         end
-        ret = if H == MaybeConstruct
-            quote
-                # TODO: last type instability.
-                # replace this with val => Changed(), val => Unchanged()
-                # return values. 
-                #
-                # Don't construct when we don't absolutely have to.
-                # `constructorof` may not be defined for an object.
-                if props === new_props
-                    return _maybeitr(obj, itr)
-                else
-                    return _maybeitr($ctr(new_props...), itr)
-                end
-            end
-        else 
-            ret = :(return _maybeitr($ctr(new_props...), itr))
+    end
+end
+@generated function mapobject(f, obj::O, ::Fields, handler::H, itr::Int) where {O,H}
+    # TODO: This is how Flatten.jl works, but it's not really 
+    # correct use of ConstructionBase as it assumers properties=fields
+    fnames = fieldnames(O)
+    ctr = _constructor(H(), O)
+    if isempty(fnames)
+        :(return (obj, itr) => Unchanged())
+    else
+        prop_args = map(fn -> :(getfield(obj, $(QuoteNode(fn)))), fnames)
+        prop_exp = Expr(:tuple, prop_args...)
+        ### Unrolled iterating function appliation (it will compile away) ####
+        # Each function call also updates the iterator value in local scoope with 
+        # the return value from the function. But it only actually inserts the 
+        # value into the parent tuple.
+        val_exps = map(prop_args) do pa
+            :(((val, itr), change) = f($pa, itr); val => change)
         end
+        new_prop_exp = Expr(:tuple, val_exps...)
         quote 
             props = $prop_exp
             new_props = $new_prop_exp
-            $ret
+            new_props, change = _splitchanged(new_props) 
+            # Don't construct when we don't absolutely have to.
+            # `constructorof` may not be defined for an object.
+            if change isa Changed
+                return ($ctr(new_props...), itr) => change
+            else
+                return (obj, itr) => change
+            end
         end
     end
 end
 
+_splitchanged(props) = map(first, props), _findchanged(map(last, props))
+
+_findchanged(::Tuple{Changed,Vararg}) = Changed()
+_findchanged(cs::Tuple) = _findchanged(Base.tail(cs))
+_findchanged(::Tuple{}) = Unchanged()
+
 _maybeitr(x, ::Nothing) = x
 _maybeitr(x, itr) = x, itr
 
+_maybeskip(::Skip, v) = ()
+_maybeskip(x, v) = v
+
 """
     Recursive(descent_condition, optic)
 
@@ -499,7 +502,7 @@ Query(select, descend = x -> true) = Query(select, descend, Fields())
 Query(; select=Any, descend=x -> true, optic=Fields()) = Query(select, descend, optic)
 
 function (q::Query)(obj)
-    mapobject(obj, _inner(q.optic), Splat(), nothing) do o
+    mapobject(obj, _inner(q.optic), Skip(), nothing) do o
         if q.select_condition(o)
             (_getouter(o, q.optic),)
         elseif q.descent_condition(o)
@@ -510,16 +513,16 @@ function (q::Query)(obj)
     end
 end
 
-set(obj, q::Query, vals) = _set(obj, q::Query, (vals, 1))[1]
+set(obj, q::Query, vals) = _set(obj, q::Query, (vals, 1))[1][1]
 
 function _set(obj, q::Query, (vals, itr))
-    mapobject(obj, _inner(q.optic), Construct(), itr) do o, itr
+    mapobject(obj, _inner(q.optic), MaybeConstruct(), itr) do o, itr
         if q.select_condition(o)
-            _setouter(o, q.optic, vals[itr]), itr + 1
+            (_setouter(o, q.optic, vals[itr]), itr + 1) => Changed()
         elseif q.descent_condition(o)
             _set(o, q, (vals, itr))
         else
-            o, itr
+            (o, itr) => Unchanged()
         end
     end
 end
diff --git a/test/test_queries.jl b/test/test_queries.jl
index 592d8cfd..96bc2236 100644
--- a/test/test_queries.jl
+++ b/test/test_queries.jl
@@ -26,11 +26,14 @@ println("get")
 @btime $slowlens($obj)
 @test lens(obj) == slowlens(obj) == (17.0, 6.0)
 
+missings_obj = (a=missing, b=1, c=(d=missing, e=(f=missing, g=2)))
+@test Query(ismissing)(missings_obj) === (missing, missing, missing)
+
 println("set")
 # Need a wrapper so we don't have to pass in the starting iterator
 @btime Accessors.set($obj, $lens, $vals)
 @btime Accessors._set($obj, $lens, ($vals, 1))[1]
-@btime Accessors.set($obj, $slowlens, $vals)
+# @btime Accessors.set($obj, $slowlens, $vals)
 Accessors.set(obj, lens, vals) 
 @test Accessors.set(obj, lens, vals) == 
     Accessors.set(obj, lens, vals) == 
@@ -47,3 +50,4 @@ unstable_lens = Accessors.Query(select=x -> x isa Float64 && x > 2, descend=x ->
 # Somehow modify compiles away almost completely
 @btime modify(x -> 10x, $obj, $lens)
 @test modify(x -> 10x, obj, lens) == (7, (a=170.0, b=2.0f0), ("3", 4, 5.0), ((a=60.0,), [1]))
+