diff --git a/src/PDF/Layer.hs b/src/PDF/Layer.hs
index 1b6afdc..7b57129 100644
--- a/src/PDF/Layer.hs
+++ b/src/PDF/Layer.hs
@@ -55,7 +55,7 @@ instance Output Layer where
 
 data AllObjects = AllObjects
 
-instance MonadFail m => Box m AllObjects Layer (Map ObjectId Object) where
+instance Monad m => Box m AllObjects Layer (Map ObjectId Object) where
   r AllObjects = return . objects
   w AllObjects layer@(Layer {occurrences, docStructure}) newObjects =
     return $ layer {