diff --git a/cohttp-lwt-jsoo/src/cohttp_lwt_jsoo.ml b/cohttp-lwt-jsoo/src/cohttp_lwt_jsoo.ml
index b0422d743..2d6802431 100644
--- a/cohttp-lwt-jsoo/src/cohttp_lwt_jsoo.ml
+++ b/cohttp-lwt-jsoo/src/cohttp_lwt_jsoo.ml
@@ -188,7 +188,7 @@ struct
   (* No implementation (can it be done?).  What should the failure exception be? *)
   exception Cohttp_lwt_xhr_callv_not_implemented
 
-  let callv ?ctx:_ _uri _reqs = Lwt.fail Cohttp_lwt_xhr_callv_not_implemented
+  let callv ?ctx:_ _uri _reqs = raise Cohttp_lwt_xhr_callv_not_implemented
 
   (* ??? *)
 end
diff --git a/cohttp-lwt-unix/src/io.ml b/cohttp-lwt-unix/src/io.ml
index 2e22cb952..0fd496dd6 100644
--- a/cohttp-lwt-unix/src/io.ml
+++ b/cohttp-lwt-unix/src/io.ml
@@ -40,12 +40,12 @@ let wrap_read f ~if_closed =
      https://github.com/ocsigen/lwt/pull/635 *)
   Lwt.catch f (function
     | Lwt_io.Channel_closed _ -> Lwt.return if_closed
-    | Unix.Unix_error _ as e -> Lwt.fail (IO_error e)
+    | Unix.Unix_error _ as e -> raise (IO_error e)
     | exn -> raise exn)
 
 let wrap_write f =
   Lwt.catch f (function
-    | Unix.Unix_error _ as e -> Lwt.fail (IO_error e)
+    | Unix.Unix_error _ as e -> raise (IO_error e)
     | exn -> raise exn)
 
 let read_line ic =
diff --git a/cohttp-lwt-unix/src/server.ml b/cohttp-lwt-unix/src/server.ml
index 2f581f907..6aa5ccd90 100644
--- a/cohttp-lwt-unix/src/server.ml
+++ b/cohttp-lwt-unix/src/server.ml
@@ -16,8 +16,8 @@ let respond_file ?headers ~fname () =
     (fun () ->
       (* Check this isn't a directory first *)
       ( fname |> Lwt_unix.stat >>= fun s ->
-        if Unix.(s.st_kind <> S_REG) then Lwt.fail Isnt_a_file
-        else Lwt.return_unit )
+        if Unix.(s.st_kind <> S_REG) then raise Isnt_a_file else Lwt.return_unit
+      )
       >>= fun () ->
       let count = 16384 in
       Lwt_io.open_file ~buffer:(Lwt_bytes.create count) ~mode:Lwt_io.input fname
diff --git a/cohttp-lwt-unix/test/test_client.ml b/cohttp-lwt-unix/test/test_client.ml
index 07c652088..8ab5c34bd 100644
--- a/cohttp-lwt-unix/test/test_client.ml
+++ b/cohttp-lwt-unix/test/test_client.ml
@@ -59,13 +59,13 @@ let methods (handler : Cohttp_lwt.S.call) uri =
     handler `GET Uri.(with_path uri k) >>= fun (res, body) ->
     match Response.status res with
     | `OK | `No_content -> Body.to_string body
-    | _ -> Body.drain_body body >>= fun () -> Lwt.fail Not_found
+    | _ -> Body.drain_body body >>= fun () -> raise Not_found
   and delete k =
     handler `DELETE Uri.(with_path uri k) >>= fun (res, body) ->
     Body.drain_body body >>= fun () ->
     match Response.status res with
     | `OK | `No_content -> Lwt.return_unit
-    | _ -> Lwt.fail Not_found
+    | _ -> raise Not_found
   and mem k =
     handler `HEAD Uri.(with_path uri k) >>= fun (res, body) ->
     Body.drain_body body >|= fun () ->
@@ -171,7 +171,7 @@ let test_unknown uri =
             connection := c;
             match body with
             (* Still, body may have been (partially) consumed and needs re-creation. *)
-            | Some (`Stream _) -> Lwt.fail Connection.Retry
+            | Some (`Stream _) -> raise Connection.Retry
             | None | Some (`Empty | `String _ | `Strings _) ->
                 handler ?headers ?body meth uri)
         | e -> Lwt.reraise e)
diff --git a/cohttp-lwt/src/connection.ml b/cohttp-lwt/src/connection.ml
index a4b94916a..879ed0810 100644
--- a/cohttp-lwt/src/connection.ml
+++ b/cohttp-lwt/src/connection.ml
@@ -172,7 +172,7 @@ module Make (Net : S.Net) : S.Connection with module Net = Net = struct
         Queue.push { uri; meth; headers; body; res_r } connection.waiting;
         Lwt_condition.broadcast connection.condition ();
         res
-    | Closing _ | Half _ | Closed | Failed _ -> Lwt.fail Retry
+    | Closing _ | Half _ | Closed | Failed _ -> raise Retry
 
   let rec writer connection =
     match connection.state with
diff --git a/cohttp-lwt/src/connection_cache.ml b/cohttp-lwt/src/connection_cache.ml
index 74a584111..0dd46432d 100644
--- a/cohttp-lwt/src/connection_cache.ml
+++ b/cohttp-lwt/src/connection_cache.ml
@@ -161,9 +161,9 @@ end = struct
         (function
           | Retry -> (
               match body with
-              | Some (`Stream _) -> Lwt.fail Retry
+              | Some (`Stream _) -> raise Retry
               | None | Some `Empty | Some (`String _) | Some (`Strings _) ->
-                  if retry <= 0 then Lwt.fail Retry else request (retry - 1))
+                  if retry <= 0 then raise Retry else request (retry - 1))
           | e -> Lwt.reraise e)
     in
     request self.retry
diff --git a/cohttp-mirage/src/input_channel.ml b/cohttp-mirage/src/input_channel.ml
index 96e2e6210..7b1b1f3b6 100644
--- a/cohttp-mirage/src/input_channel.ml
+++ b/cohttp-mirage/src/input_channel.ml
@@ -13,7 +13,7 @@ module Make (Channel : Mirage_channel.S) = struct
         Cstruct.blit_to_bytes v 0 buf pos len;
         Lwt.return (`Ok len)
     | Ok `Eof -> Lwt.return `Eof
-    | Error e -> Lwt.fail (Read_exn e)
+    | Error e -> raise (Read_exn e)
 
   let create ?(buf_len = 0x4000) chan =
     { buf = Bytebuffer.create buf_len; chan }
diff --git a/cohttp-mirage/src/io.ml b/cohttp-mirage/src/io.ml
index 1e20f8b03..d8215037a 100644
--- a/cohttp-mirage/src/io.ml
+++ b/cohttp-mirage/src/io.ml
@@ -55,7 +55,7 @@ module Make (Channel : Mirage_channel.S) = struct
     Channel.flush oc >>= function
     | Ok () -> Lwt.return_unit
     | Error `Closed -> failwith "Trying to write on closed channel"
-    | Error e -> Lwt.fail (Write_exn e)
+    | Error e -> raise (Write_exn e)
 
   let flush _ =
     (* NOOP since we flush in the normal writer functions above *)