diff --git a/builder-web.opam b/builder-web.opam
index c4e164c..5dfd9a0 100644
--- a/builder-web.opam
+++ b/builder-web.opam
@@ -22,7 +22,7 @@ depends: [
   "cstruct" {>= "6.0.0"}
   "bos"
   "hex"
-  "lwt" {>= "5.3.0"}
+  "lwt" {>= "5.6.0"}
   "caqti" {>= "1.8.0"}
   "caqti-lwt"
   "caqti-driver-sqlite3"
diff --git a/lib/builder_web.ml b/lib/builder_web.ml
index 24e5126..7d4e24a 100644
--- a/lib/builder_web.ml
+++ b/lib/builder_web.ml
@@ -240,7 +240,7 @@ module Viz_aux = struct
         (Fpath.to_string viz_path)
         Lwt_io.read
     )
-    |> Lwt_result.map_err (fun exn -> `Msg (Printexc.to_string exn))
+    |> Lwt_result.map_error (fun exn -> `Msg (Printexc.to_string exn))
     |> if_error "Error getting cached visualization"
 
 end
diff --git a/lib/model.ml b/lib/model.ml
index 8df5791..d7f9cc7 100644
--- a/lib/model.ml
+++ b/lib/model.ml
@@ -315,7 +315,7 @@ let add_build
   let job_name = job.Builder.name in
   let staging_dir = Fpath.(staging datadir / Uuidm.to_string uuid) in
   let or_cleanup x =
-    Lwt_result.map_err (fun e ->
+    Lwt_result.map_error (fun e ->
         Bos.OS.Dir.delete ~recurse:true staging_dir
         |> Result.iter_error (fun e ->
             Log.err (fun m -> m "Failed to remove staging dir %a: %a"
@@ -405,7 +405,7 @@ let add_build
     commit_files datadir staging_dir job_name uuid >|= fun () ->
     main_binary
   in
-  Lwt_result.bind_lwt_err (or_cleanup r)
+  Lwt_result.bind_lwt_error (or_cleanup r)
     (fun e ->
        Db.rollback ()
        |> Lwt.map (fun r ->