diff --git a/test/lib/test_contributions.ml b/test/lib/test_contributions.ml
index b91326f..1c760e7 100644
--- a/test/lib/test_contributions.ml
+++ b/test/lib/test_contributions.ml
@@ -66,9 +66,16 @@ module Testable = struct
         (Repo_map.pp (Format.pp_print_list Item.pp))
         x.activity
 
+    (* [List.equal] requires OCaml >= 4.12 *)
+    let list_equal eq lx ly =
+      try
+        List.iter2 (fun x y -> if not (eq x y) then failwith "not equal") lx ly;
+        true
+      with _ -> false
+
     let eq (x : t) (y : t) =
       String.equal x.username y.username
-      && Repo_map.eq (List.equal Item.eq) x.activity y.activity
+      && Repo_map.eq (list_equal Item.eq) x.activity y.activity
 
     let testable = Alcotest.testable pp eq
   end