diff --git a/src/Scope.ml b/src/Scope.ml
index cc5ca19b..26abc9aa 100644
--- a/src/Scope.ml
+++ b/src/Scope.ml
@@ -21,10 +21,10 @@ struct
     module M = Algaeff.Mutex.Make()
 
     type scope = {visible : (data, tag) Trie.t; export : (data, tag) Trie.t}
-    module S = Algaeff.State.Make(struct type state = scope end)
+    module S = Algaeff.State.Make(struct type t = scope end)
 
     type env = {export_prefix : Trie.bwd_path}
-    module R = Algaeff.Reader.Make(struct type nonrec env = env end)
+    module R = Algaeff.Reader.Make(struct type t = env end)
 
     let run ~export_prefix ~init_visible f =
       let env = {export_prefix} in
diff --git a/src/Trie.ml b/src/Trie.ml
index e3b055a3..1335eb8c 100644
--- a/src/Trie.ml
+++ b/src/Trie.ml
@@ -297,7 +297,7 @@ let filter ?prefix f = filter_map ?prefix @@
 (** {1 Conversion from/to Seq} *)
 
 let to_seq_with_bwd_paths (type data) (type tag) ?prefix (t : (data, tag) t) =
-  let module S = Algaeff.Sequencer.Make (struct type elt = bwd_path * (data * tag) end) in
+  let module S = Algaeff.Sequencer.Make (struct type t = bwd_path * (data * tag) end) in
   S.run @@ fun () -> iter ?prefix (fun p (d, t) -> S.yield (p, (d, t))) t
 
 let to_seq_values t = Seq.map snd @@
diff --git a/yuujinchou.opam b/yuujinchou.opam
index 173ab587..ab296c95 100644
--- a/yuujinchou.opam
+++ b/yuujinchou.opam
@@ -16,7 +16,7 @@ dev-repo: "git+https://github.com/RedPRL/yuujinchou.git"
 depends: [
   "dune" {>= "2.0"}
   "ocaml" {>= "5.0"}
-  "algaeff" {>= "0.2"}
+  "algaeff" {>= "2.0"}
   "bwd" {>= "2.2"}
   "alcotest" {>= "1.5" & with-test}
   "qcheck-core" {>= "0.18" & with-test}