diff --git a/library/init/functor.lean b/library/init/functor.lean
index e82209d99d..15cd5e32ce 100644
--- a/library/init/functor.lean
+++ b/library/init/functor.lean
@@ -8,7 +8,7 @@ prelude
 structure functor [class] (f : Type → Type) : Type :=
 (map : Π {a b: Type}, (a → b) → f a → f b)
 
-inline definition fmap {A B : Type} {F : Type → Type} [functor F] (f : A → B) (a : F A) : F B :=
+inline definition fmap {F : Type → Type} [functor F] {A B : Type} (f : A → B) (a : F A) : F B :=
 functor.map f a
 
 infixr ` <$> `:100 := fmap