diff --git a/src/rstd/fallible.rs b/src/rstd/fallible.rs
index 2cfcb51..e8d1d6e 100644
--- a/src/rstd/fallible.rs
+++ b/src/rstd/fallible.rs
@@ -25,7 +25,9 @@ pub trait FallibleContext<'a>: Context<'a> {
     }
 
     /// Convert a wrapped result into a fallible wrapped.
-    fn stuff<A: 'a, E: 'a>(fa: WrapC<'a, Result<A, E>, Self>) -> WrapE<'a, A, E, Self::Fallible> {
+    fn stuff<A: 'a, E: 'a>(
+        fa: WrapC<'a, Result<A, E>, Self>,
+    ) -> WrapE<'a, A, E, <Self as Context<'a>>::Fallible> {
         Self::Fallible::stuff(fa)
     }
 }