diff --git a/components/layout_2020/dom_traversal.rs b/components/layout_2020/dom_traversal.rs
index 99bf0804ce6..d5494a363bf 100644
--- a/components/layout_2020/dom_traversal.rs
+++ b/components/layout_2020/dom_traversal.rs
@@ -512,7 +512,7 @@ where
     }
 
     fn unset_all_boxes(self) {
-        let mut data = self.layout_data_mut();
+        let data = self.layout_data_mut();
         *data.self_box.borrow_mut() = None;
         *data.pseudo_before_box.borrow_mut() = None;
         *data.pseudo_after_box.borrow_mut() = None;
diff --git a/rust-toolchain b/rust-toolchain
index 8737a7eb567..38819f8f093 100644
--- a/rust-toolchain
+++ b/rust-toolchain
@@ -1 +1 @@
-nightly-2020-05-15
+nightly-2020-06-22