diff --git a/src/server.ml b/src/server.ml
index 372005ab..c529f5ef 100644
--- a/src/server.ml
+++ b/src/server.ml
@@ -308,6 +308,10 @@ module Make (IO : IO) = struct
       (** List symbols in this document.
         @since 0.3 *)
 
+      method on_unknown_request ~notify_back:(_ : notify_back) ~server_request:_ ~id:_ meth params
+          : Yojson.Safe.t IO.t =
+        IO.failwith "unhandled request"
+
       method on_request : type r.
           notify_back:_ ->
           server_request:_ ->
@@ -467,14 +471,20 @@ module Make (IO : IO) = struct
           | Lsp.Client_request.CallHierarchyOutgoingCalls _
           | Lsp.Client_request.WillCreateFiles _
           | Lsp.Client_request.WillDeleteFiles _
-          | Lsp.Client_request.WillRenameFiles _
-          | Lsp.Client_request.UnknownRequest _ ->
+          | Lsp.Client_request.WillRenameFiles _ ->
             let notify_back =
               new notify_back
                 ~workDoneToken:None ~partialResultToken:None ~notify_back
                 ~server_request ()
             in
             self#on_request_unhandled ~notify_back ~id r
+          | Lsp.Client_request.UnknownRequest r ->
+            let notify_back =
+              new notify_back
+                ~workDoneToken:None ~partialResultToken:None ~notify_back
+                ~server_request ()
+            in
+            self#on_unknown_request ~notify_back ~server_request ~id r.meth r.params
 
       method virtual on_notif_doc_did_open
           : notify_back:notify_back ->
@@ -495,6 +505,10 @@ module Make (IO : IO) = struct
             unit IO.t
       (** Called when the document changes. *)
 
+      method on_unknown_notification ~notify_back:(_ : notify_back)
+          (_n : Jsonrpc.Notification.t) : unit IO.t =
+        IO.return ()
+
       method on_notification_unhandled ~notify_back:(_ : notify_back)
           (_n : Lsp.Client_notification.t) : unit IO.t =
         IO.return ()
@@ -598,7 +612,6 @@ module Make (IO : IO) = struct
         | Lsp.Client_notification.ChangeWorkspaceFolders _
         | Lsp.Client_notification.ChangeConfiguration _
         | Lsp.Client_notification.Initialized
-        | Lsp.Client_notification.UnknownNotification _
         | Lsp.Client_notification.CancelRequest _
         | Lsp.Client_notification.WorkDoneProgressCancel _
         | Lsp.Client_notification.SetTrace _
@@ -615,5 +628,12 @@ module Make (IO : IO) = struct
           self#on_notification_unhandled
             ~notify_back:(notify_back : notify_back)
             n
+        | Lsp.Client_notification.UnknownNotification n ->
+          let notify_back =
+            new notify_back
+              ~workDoneToken:None ~partialResultToken:None ~notify_back
+              ~server_request ()
+          in
+          self#on_unknown_notification ~notify_back n
     end
 end