diff --git a/src/std.rs b/src/std.rs
index 93c17f5..5ce6f46 100644
--- a/src/std.rs
+++ b/src/std.rs
@@ -35,3 +35,37 @@ impl<S: Serializable> ExtSerializable for S {
         vec
     }
 }
+
+pub trait ExtContext: Context {
+    fn unstuff<'a, A: 'a, E: 'a>(
+        wa: <<Self::Fallible as MonadFailAny>::W<E> as WeakFunctor>::F<'a, A>,
+    ) -> <Self::T as WeakFunctor>::F<'a, Result<A, E>>
+    where
+        Self: 'a;
+
+    fn stuff<'a, A: 'a, E: 'a>(
+        fa: <Self::T as WeakFunctor>::F<'a, Result<A, E>>,
+    ) -> <<Self::Fallible as MonadFailAny>::W<E> as WeakFunctor>::F<'a, A>
+    where
+        Self: 'a;
+}
+
+impl<Ctx: Context> ExtContext for Ctx {
+    fn unstuff<'a, A: 'a, E: 'a>(
+        wa: <<Self::Fallible as MonadFailAny>::W<E> as WeakFunctor>::F<'a, A>,
+    ) -> <Self::T as WeakFunctor>::F<'a, Result<A, E>>
+    where
+        Self: 'a,
+    {
+        Self::Fallible::unstuff(wa)
+    }
+
+    fn stuff<'a, A: 'a, E: 'a>(
+        fa: <Self::T as WeakFunctor>::F<'a, Result<A, E>>,
+    ) -> <<Self::Fallible as MonadFailAny>::W<E> as WeakFunctor>::F<'a, A>
+    where
+        Self: 'a,
+    {
+        Self::Fallible::stuff(fa)
+    }
+}
diff --git a/src/std/collections/rbtree/subset.rs b/src/std/collections/rbtree/subset.rs
index 73cf1c2..e30c178 100644
--- a/src/std/collections/rbtree/subset.rs
+++ b/src/std/collections/rbtree/subset.rs
@@ -2,7 +2,7 @@ use std::rc::Rc;
 
 use crate::flow::traversible::*;
 use crate::func::*;
-use crate::std::fallible::*;
+use crate::std::{fallible::*, *};
 
 use super::*;
 
@@ -96,7 +96,7 @@ impl<'a, Ctx: 'a + Context, A: Mentionable<'a, Ctx>>
     > {
         <SubsetMonad<'a, Ctx, A> as Functor>::fmap(
             |resolved| resolved as Rc<dyn TraversibleBinaryNode<'a, _, _, _>>,
-            self.resolve(),
+            Ctx::stuff(self.resolve()),
         )
     }
 
@@ -117,7 +117,7 @@ impl<'a, Ctx: 'a + Context, A: Mentionable<'a, Ctx>>
     > {
         <SubsetMonad<'a, Ctx, A> as Functor>::fmap(
             |resolved| resolved as Rc<dyn TraversibleBinaryNode<'a, _, _, _>>,
-            self.resolve(),
+            Ctx::stuff(self.resolve()),
         )
     }
 
@@ -138,7 +138,7 @@ impl<'a, Ctx: 'a + Context, A: Mentionable<'a, Ctx>>
     > {
         <SubsetMonad<'a, Ctx, A> as Functor>::fmap(
             |resolved| resolved as Rc<dyn TraversibleBinaryNode<'a, _, _, _>>,
-            self.resolve(),
+            Ctx::stuff(self.resolve()),
         )
     }
 
diff --git a/src/std/fallible.rs b/src/std/fallible.rs
index 4a2c493..c791b04 100644
--- a/src/std/fallible.rs
+++ b/src/std/fallible.rs
@@ -1,7 +1,5 @@
-use crate::func::classes::{composition::*, result::*};
-
 use super::*;
 
-pub type FallibleMonad<Ctx, E> = CompositionClass<<Ctx as Context>::T, ResultClass<E>>;
+pub type FallibleMonad<Ctx, E> = <<Ctx as Context>::Fallible as MonadFailAny>::W<E>;
 
 pub type FallibleWrapped<'a, Ctx, A, E> = <FallibleMonad<Ctx, E> as WeakFunctor>::F<'a, A>;