diff --git a/vendors/ocaml-hacl/src/hacl.ml b/vendors/ocaml-hacl/src/hacl.ml
index 61f2a789f..f908ce296 100644
--- a/vendors/ocaml-hacl/src/hacl.ml
+++ b/vendors/ocaml-hacl/src/hacl.ml
@@ -32,7 +32,7 @@ module Rand = struct
 end
 
 module Hash = struct
-  module type S = sig
+  module type HASH = sig
     val init : Bigstring.t -> unit
     val update : Bigstring.t -> Bigstring.t -> unit
     val update_last : Bigstring.t -> Bigstring.t -> int -> unit
@@ -43,7 +43,7 @@ module Hash = struct
     val statebytes : int
   end
 
-  module Make(S: S) = struct
+  module Make(S: HASH) = struct
     type state = {
       state : Bigstring.t ;
       buf : Bigstring.t ;
@@ -87,6 +87,33 @@ module Hash = struct
       finish st
   end
 
+  module type S = sig
+    type state
+
+    val bytes : int
+    val blockbytes : int
+    val statebytes : int
+
+    (** Incremental Interface *)
+
+    val init : unit -> state
+    val update : state -> Bigstring.t -> unit
+    val finish : state -> Bigstring.t
+
+    (** Direct Interface *)
+
+    val digest : Bigstring.t -> Bigstring.t
+
+    module HMAC : sig
+      val write :
+        key:Bigstring.t -> msg:Bigstring.t -> Bigstring.t -> unit
+      (** @raise [Invalid_argument] if argument is less than 32 bytes long *)
+
+      val digest :
+        key:Bigstring.t -> msg:Bigstring.t -> Bigstring.t
+    end
+  end
+
   module SHA256 = struct
     module H = Make(struct
         (* state -> unit *)
diff --git a/vendors/ocaml-hacl/src/hacl.mli b/vendors/ocaml-hacl/src/hacl.mli
index 7559c3013..c95a53709 100644
--- a/vendors/ocaml-hacl/src/hacl.mli
+++ b/vendors/ocaml-hacl/src/hacl.mli
@@ -28,7 +28,7 @@ module Rand : sig
 end
 
 module Hash : sig
-  module SHA256 : sig
+  module type S = sig
     type state
 
     val bytes : int
@@ -55,32 +55,8 @@ module Hash : sig
     end
   end
 
-  module SHA512 : sig
-    type state
-
-    val bytes : int
-    val blockbytes : int
-    val statebytes : int
-
-    (** Incremental Interface *)
-
-    val init : unit -> state
-    val update : state -> Bigstring.t -> unit
-    val finish : state -> Bigstring.t
-
-    (** Direct Interface *)
-
-    val digest : Bigstring.t -> Bigstring.t
-
-    module HMAC : sig
-      val write :
-        key:Bigstring.t -> msg:Bigstring.t -> Bigstring.t -> unit
-      (** @raise [Invalid_argument] if argument is less than 32 bytes long *)
-
-      val digest :
-        key:Bigstring.t -> msg:Bigstring.t -> Bigstring.t
-    end
-  end
+  module SHA256 : S
+  module SHA512 : S
 end
 
 module Nonce : sig