diff --git a/src/rstd/fallible.rs b/src/rstd/fallible.rs
index 91ab300..2cfcb51 100644
--- a/src/rstd/fallible.rs
+++ b/src/rstd/fallible.rs
@@ -18,7 +18,9 @@ pub type FallibleWrapped<'a, Ctx, A, E> = Wrap<'a, A, FallibleMonad<'a, Ctx, E>>
 /// this is the preferred way to switch between [Wrapped] and [fallible].
 pub trait FallibleContext<'a>: Context<'a> {
     /// Convert a fallible wrapped into a wrapped result.
-    fn unstuff<A: 'a, E: 'a>(wa: WrapE<'a, A, E, Self::Fallible>) -> WrapC<'a, Result<A, E>, Self> {
+    fn unstuff<A: 'a, E: 'a>(
+        wa: WrapE<'a, A, E, <Self as Context<'a>>::Fallible>,
+    ) -> WrapC<'a, Result<A, E>, Self> {
         Self::Fallible::unstuff(wa)
     }