diff --git a/rust/hg-cpython/src/ref_sharing.rs b/rust/hg-cpython/src/ref_sharing.rs
--- a/rust/hg-cpython/src/ref_sharing.rs
+++ b/rust/hg-cpython/src/ref_sharing.rs
@@ -345,7 +345,7 @@
             $name,
             $leaked,
             Box<
-                Iterator<Item = (&'static $key_type, &'static $value_type)>
+                dyn Iterator<Item = (&'static $key_type, &'static $value_type)>
                     + Send,
             >,
             $success_func,
@@ -367,7 +367,7 @@
         py_shared_iterator_impl!(
             $name,
             $leaked,
-            Box<Iterator<Item = &'static $key_type> + Send>,
+            Box<dyn Iterator<Item = &'static $key_type> + Send>,
             $success_func,
             $success_type
         );