diff --git a/.ocamlformat b/.ocamlformat
index d59e16a..f57d502 100644
--- a/.ocamlformat
+++ b/.ocamlformat
@@ -1,4 +1,4 @@
-version = 0.14.2
+version = 0.16.0
 break-infix = fit-or-vertical
 parse-docstrings = true
 indicate-multiline-delimiters=no
diff --git a/duff.opam b/duff.opam
index 358a456..60d8d09 100644
--- a/duff.opam
+++ b/duff.opam
@@ -27,7 +27,7 @@ depends: [
   "stdlib-shims"
   "alcotest"    {with-test}
   "bigstringaf" {with-test}
-  "hxd"         {with-test}
+  "hxd"         {with-test & >= "0.3.1"}
   "crowbar"     {with-test}
 ]
 
diff --git a/fuzz/fuzz.ml b/fuzz/fuzz.ml
index 4b9b6a3..477aabe 100644
--- a/fuzz/fuzz.ml
+++ b/fuzz/fuzz.ml
@@ -2,7 +2,8 @@ open Crowbar
 
 let length l =
   List.fold_left
-    (fun a -> function Duff.Copy (_, len) -> a + len
+    (fun a -> function
+      | Duff.Copy (_, len) -> a + len
       | Duff.Insert (_, len) -> a + len)
     0 l
 
@@ -32,5 +33,5 @@ let () =
   apply ~len:length a b c rabin ;
 
   check_eq
-    ~pp:(Hxd_string.pp Hxd.O.default)
+    ~pp:(Hxd_string.pp Hxd.default)
     ~eq:String.equal (Bigstringaf.to_string b) (Bigstringaf.to_string c)
diff --git a/test/test.ml b/test/test.ml
index d1ebb65..c9b1336 100644
--- a/test/test.ml
+++ b/test/test.ml
@@ -33,7 +33,8 @@ let test length =
   let rabin = Duff.delta index ~source ~target in
   let length' =
     List.fold_left
-      (fun a -> function Duff.Copy (_, len) -> a + len
+      (fun a -> function
+        | Duff.Copy (_, len) -> a + len
         | Duff.Insert (_, len) -> a + len)
       0 rabin in