diff --git a/.github/workflows/ocaml.yml b/.github/workflows/ocaml.yml
index 8680d82..51dd5d1 100644
--- a/.github/workflows/ocaml.yml
+++ b/.github/workflows/ocaml.yml
@@ -9,8 +9,7 @@ jobs:
     strategy:
       matrix:
         include:
-          - ocaml-compiler: "ocaml-base-compiler.5.0.0"
-          - ocaml-compiler: "ocaml-base-compiler.5.1.1"
+          - ocaml-compiler: "ocaml-base-compiler.5.3.0~alpha1"
             with-doc: true
     runs-on: ubuntu-latest
     steps:
diff --git a/algaeff.opam b/algaeff.opam
index 9773024..1b003bb 100644
--- a/algaeff.opam
+++ b/algaeff.opam
@@ -12,7 +12,7 @@ bug-reports: "https://github.com/RedPRL/algaeff/issues"
 dev-repo: "git+https://github.com/RedPRL/algaeff.git"
 depends: [
   "dune" {>= "2.0"}
-  "ocaml" {>= "5.0"}
+  "ocaml" {>= "5.3"}
   "alcotest" {>= "1.5" & with-test}
   "qcheck-core" {>= "0.18" & with-test}
   "odoc" {with-doc}
diff --git a/src/Reader.ml b/src/Reader.ml
index 6faabd9..5d078d2 100644
--- a/src/Reader.ml
+++ b/src/Reader.ml
@@ -9,18 +9,13 @@ end
 
 module Make (Env : Sigs.Type) =
 struct
-  type _ Effect.t += Read : Env.t Effect.t
+  type _ eff += Read : Env.t eff
 
   let read () = Effect.perform Read
 
   let run ~(env:Env.t) f =
     let open Effect.Deep in
-    try_with f ()
-      { effc = fun (type a) (eff : a Effect.t) ->
-            match eff with
-            | Read -> Option.some @@ fun (k : (a, _) continuation) ->
-              continue k env
-            | _ -> None }
+    try f () with effect Read, k -> continue k env
 
   let scope f c = run ~env:(f @@ read ()) c
 
diff --git a/src/Sequencer.ml b/src/Sequencer.ml
index c2f89b6..9896b2f 100644
--- a/src/Sequencer.ml
+++ b/src/Sequencer.ml
@@ -8,18 +8,14 @@ end
 
 module Make (Elt : Sigs.Type) =
 struct
-  type _ Effect.t += Yield : Elt.t -> unit Effect.t
+  type _ eff += Yield : Elt.t -> unit eff
 
   let yield x = Effect.perform (Yield x)
 
   let run f () =
     let open Effect.Deep in
-    try_with (fun () -> f (); Seq.Nil) ()
-      { effc = fun (type a) (eff : a Effect.t) ->
-            match eff with
-            | Yield x -> Option.some @@ fun (k : (a, _) continuation) ->
-              Seq.Cons (x, continue k)
-            | _ -> None }
+    try f (); Seq.Nil with
+    | effect Yield x, k -> Seq.Cons (x, continue k)
 
   let register_printer f = Printexc.register_printer @@ function
     | Effect.Unhandled (Yield elt) -> f (`Yield elt)
diff --git a/src/State.ml b/src/State.ml
index 88331be..4e2f46b 100644
--- a/src/State.ml
+++ b/src/State.ml
@@ -11,9 +11,9 @@ end
 
 module Make (State : Sigs.Type) =
 struct
-  type _ Effect.t +=
-    | Get : State.t Effect.t
-    | Set : State.t -> unit Effect.t
+  type _ eff +=
+    | Get : State.t eff
+    | Set : State.t -> unit eff
 
   let get () = Effect.perform Get
   let set st = Effect.perform (Set st)
@@ -21,25 +21,15 @@ struct
   let run ~(init:State.t) f =
     let open Effect.Deep in
     let st = ref init in
-    try_with f ()
-      { effc = fun (type a) (eff : a Effect.t) ->
-            match eff with
-            | Get -> Option.some @@ fun (k : (a, _) continuation) ->
-              continue k !st
-            | Set v -> Option.some @@ fun (k : (a, _) continuation) ->
-              st := v; continue k ()
-            | _ -> None }
+    try f () with
+    | effect Get, k -> continue k !st
+    | effect Set v, k -> st := v; continue k ()
 
   let try_with ?(get=get) ?(set=set) f =
     let open Effect.Deep in
-    try_with f ()
-      { effc = fun (type a) (eff : a Effect.t) ->
-            match eff with
-            | Get -> Option.some @@ fun (k : (a, _) continuation) ->
-              continue k (get ())
-            | Set v -> Option.some @@ fun (k : (a, _) continuation) ->
-              set v; continue k ()
-            | _ -> None }
+    try f () with
+    | effect Get, k -> continue k (get ())
+    | effect Set v, k -> set v; continue k ()
 
   let modify f = set @@ f @@ get ()
 
diff --git a/src/UniqueID.ml b/src/UniqueID.ml
index eb0b5e8..557e183 100644
--- a/src/UniqueID.ml
+++ b/src/UniqueID.ml
@@ -31,10 +31,10 @@ struct
   end
   type id = int
 
-  type _ Effect.t +=
-    | Register : Elt.t -> id Effect.t
-    | Retrieve : id -> Elt.t Effect.t
-    | Export : Elt.t Seq.t Effect.t
+  type _ eff +=
+    | Register : Elt.t -> id eff
+    | Retrieve : id -> Elt.t eff
+    | Export : Elt.t Seq.t eff
 
   let register x = Effect.perform (Register x)
   let retrieve i = Effect.perform (Retrieve i)
@@ -47,19 +47,16 @@ struct
     let init = M.of_seq @@ Seq.zip (Seq.ints 0) init in
     Eff.run ~init @@ fun () ->
     let open Effect.Deep in
-    try_with f ()
-      { effc = fun (type a) (eff : a Effect.t) ->
-            match eff with
-            | Register x -> Option.some @@ fun (k : (a, _) continuation) ->
-              let st = Eff.get () in
-              let next = M.cardinal st in
-              Eff.set @@ M.add next x st;
-              continue k next
-            | Retrieve i -> Option.some @@ fun (k : (a, _) continuation) ->
-              continue k @@ M.find i @@ Eff.get ()
-            | Export -> Option.some @@ fun (k : (a, _) continuation) ->
-              continue k @@ Seq.map snd @@ M.to_seq @@ Eff.get ()
-            | _ -> None }
+    try f () with
+    | effect Register x, k ->
+      let st = Eff.get () in
+      let next = M.cardinal st in
+      Eff.set @@ M.add next x st;
+      continue k next
+    | effect Retrieve i, k ->
+      continue k @@ M.find i @@ Eff.get ()
+    | effect Export, k ->
+      continue k @@ Seq.map snd @@ M.to_seq @@ Eff.get ()
 
   let register_printer f = Printexc.register_printer @@ function
     | Effect.Unhandled (Register elt) -> f (`Register elt)