diff --git a/src/func.rs b/src/func.rs
index 23be49b..e71d2c3 100644
--- a/src/func.rs
+++ b/src/func.rs
@@ -204,23 +204,20 @@ pub trait Monad: Applicative {
     }
 }
 
-pub trait MonadExt: Monad {
+pub trait MonadExt<'a>: 'a + Monad {
     /// [`FnMut`] version of [`Monad::iterate`].
     /// Reasoning for this method existing at all is that
     /// most usecases are better modelled with [`FnMut`]
     /// rather than some dedicated state type.
-    fn iterate_mut<'a, A: 'a, B: 'a>(
+    fn iterate_mut<A: 'a, B: 'a>(
         a: A,
         f: impl 'a + FnMut(A) -> Self::F<'a, ControlFlow<B, A>>,
-    ) -> Self::F<'a, B>
-    where
-        Self: 'a,
-    {
+    ) -> Self::F<'a, B> {
         Self::iterate(BindableMut::new(a, f))
     }
 }
 
-impl<T: Monad> MonadExt for T {}
+impl<'a, T: 'a + Monad> MonadExt<'a> for T {}
 
 /// Part of [`MonadFail`] responsible for Haskell's `fail`.
 pub trait Fail<E>: WeakFunctor {