diff --git a/examples/passing/DerivingFunctor.purs b/examples/passing/DerivingFunctor.purs
index 765564bb91..18c4deed90 100644
--- a/examples/passing/DerivingFunctor.purs
+++ b/examples/passing/DerivingFunctor.purs
@@ -15,9 +15,11 @@ data M f a
   | M4 (MyRecord a)
 
 derive instance eqM :: (Eq1 f, Eq a) => Eq (M f a)
-
 derive instance functorM :: Functor f => Functor (M f)
 
+data T a = T (forall t. Show t => t -> a)
+derive instance functorT :: Functor T
+
 type MA = M Array
 
 main = do
@@ -26,4 +28,9 @@ main = do
   assert $ map show (M2 [0, 1] :: MA Int) == M2 ["0", "1"]
   assert $ map show (M3 {foo: 0, bar: 1, baz: [2, 3]} :: MA Int) == M3 {foo: 0, bar: "1", baz: ["2", "3"]}
   assert $ map show (M4 { myField: 42 }) == M4 { myField: "42" } :: MA String
+
+  case map show (T \_ -> 42) of
+    T f -> assert $ f "hello" == "42"
+    _   -> assert false
+
   log "Done"
diff --git a/src/Language/PureScript/Sugar/TypeClasses/Deriving.hs b/src/Language/PureScript/Sugar/TypeClasses/Deriving.hs
index 1d8100f1fe..678e6274ed 100755
--- a/src/Language/PureScript/Sugar/TypeClasses/Deriving.hs
+++ b/src/Language/PureScript/Sugar/TypeClasses/Deriving.hs
@@ -742,6 +742,12 @@ deriveFunctor ss mn syns ds tyConNm = do
                     mkAssignment ((Label l), x) = (l, App x (Accessor l argVar))
                 return (lam ss arg (ObjectUpdate argVar (mkAssignment <$> updates)))
 
+          -- quantifiers
+          goType (ForAll scopedVar t _) | scopedVar /= iTyName = goType t
+
+          -- constraints
+          goType (ConstrainedType _ t) = goType t
+
           -- under a `* -> *`, just assume functor for now
           goType (TypeApp _ t) = fmap (App mapVar) <$> goType t