diff --git a/.github/workflows/opam.yml b/.github/workflows/opam.yml
index a37c40978..c7f428e40 100644
--- a/.github/workflows/opam.yml
+++ b/.github/workflows/opam.yml
@@ -18,6 +18,7 @@ jobs:
     strategy:
       matrix:
         ocaml-compiler:
+          - 4.13.x
           - 4.14.x
           - 5.0.0
           - ocaml-variants.5.1.0+trunk
diff --git a/dune-project b/dune-project
index d96eedeca..72fd5dbc8 100644
--- a/dune-project
+++ b/dune-project
@@ -47,7 +47,7 @@ and explained by some sequential interleaving.")
  (tags ("test" "property" "qcheck" "quickcheck" "parallelism" "sequential consistency"))
  (depopts base-domains)
  (depends
-  (ocaml (>= 4.14))
+  (ocaml (>= 4.13))
   (qcheck-core           (>= "0.20"))
   (qcheck-multicoretests-util (= :version))
   (ppx_deriving          (and :with-test (>= "5.2.1")))))
diff --git a/lib/lin.ml b/lib/lin.ml
index 169e2da13..ab7b12873 100644
--- a/lib/lin.ml
+++ b/lib/lin.ml
@@ -198,10 +198,13 @@ let array : type a c s. (a, c, s, combinable) ty -> (a array, c, s, combinable)
     | GenDeconstr (arb, print, eq) -> GenDeconstr (QCheck.array arb, QCheck.Print.array print, Array.for_all2 eq)
     | Deconstr (print, eq) -> Deconstr (QCheck.Print.array print, Array.for_all2 eq)
 
+let seq_iteri f s =
+  let (_:int) = Seq.fold_left (fun i x -> f i x; i + 1) 0 s in ()
+
 let print_seq pp s =
   let b = Buffer.create 25 in
   Buffer.add_char b '<';
-  Seq.iteri (fun i x ->
+  seq_iteri (fun i x ->
       if i > 0 then Buffer.add_string b "; ";
       Buffer.add_string b (pp x))
     s;
@@ -215,11 +218,18 @@ let arb_seq a =
   let gen = Gen.map List.to_seq (Gen.list a.gen) in
   QCheck.make ?print ~shrink gen
 
+let rec seq_equal eq s1 s2 =
+  let open Seq in
+  match s1 (), s2 () with
+  | Nil, Nil -> true
+  | Cons (a, an), Cons (b, bn) when eq a b -> seq_equal eq an bn
+  | _ -> false
+
 let seq : type a c s. (a, c, s, combinable) ty -> (a Seq.t, c, s, combinable) ty =
   fun ty -> match ty with
     | Gen (arb, print) -> Gen (arb_seq arb, print_seq print)
-    | GenDeconstr (arb, print, eq) -> GenDeconstr (arb_seq arb, print_seq print, Seq.equal eq)
-    | Deconstr (print, eq) -> Deconstr (print_seq print, Seq.equal eq)
+    | GenDeconstr (arb, print, eq) -> GenDeconstr (arb_seq arb, print_seq print, seq_equal eq)
+    | Deconstr (print, eq) -> Deconstr (print_seq print, seq_equal eq)
 
 let state = State
 let t = state
diff --git a/qcheck-lin.opam b/qcheck-lin.opam
index c30b2e1bc..e9a1742c9 100644
--- a/qcheck-lin.opam
+++ b/qcheck-lin.opam
@@ -22,7 +22,7 @@ homepage: "https://github.com/ocaml-multicore/multicoretests"
 bug-reports: "https://github.com/ocaml-multicore/multicoretests/issues"
 depends: [
   "dune" {>= "3.0"}
-  "ocaml" {>= "4.14"}
+  "ocaml" {>= "4.13"}
   "qcheck-core" {>= "0.20"}
   "qcheck-multicoretests-util" {= version}
   "ppx_deriving" {with-test & >= "5.2.1"}