diff --git a/src/layout/layer.rs b/src/layout/layer.rs
index dc10ffe..099202c 100644
--- a/src/layout/layer.rs
+++ b/src/layout/layer.rs
@@ -163,7 +163,7 @@ impl<'a> Iterator for LayerIteratorMut<'a> {
         let i = self.inner.next()?;
         // SAFETY: requires index iterator to work properly
         #[allow(mutable_transmutes)]
-        let layer: &mut Layer = unsafe { std::mem::transmute(&self.inner.vec[i].data) };
+        let layer = unsafe { std::mem::transmute::<&Layer, &mut Layer>(&self.inner.vec[i].data) };
         Some((i, layer))
     }
 }
@@ -173,7 +173,7 @@ impl<'a> DoubleEndedIterator for LayerIteratorMut<'a> {
         let i = self.inner.next_back()?;
         // SAFETY: requires index iterator to work properly
         #[allow(mutable_transmutes)]
-        let layer: &mut Layer = unsafe { std::mem::transmute(&self.inner.vec[i].data) };
+        let layer = unsafe { std::mem::transmute::<&Layer, &mut Layer>(&self.inner.vec[i].data) };
         Some((i, layer))
     }
 }