diff --git a/dune-project b/dune-project
index 426419d020a..a0eb608d7c6 100644
--- a/dune-project
+++ b/dune-project
@@ -195,6 +195,8 @@ understood by dune language."))
 (package
  (name ocamlc-loc)
  (synopsis "Parse ocaml compiler output into structured form")
+ (conflicts
+  (ocaml-lsp-server (< 1.15.0)))
  (depends
   (ocaml (>= 4.08.0))
   (dyn (= :version)))
diff --git a/ocamlc-loc.opam b/ocamlc-loc.opam
index a11cc1ee0a1..ddafa9f3055 100644
--- a/ocamlc-loc.opam
+++ b/ocamlc-loc.opam
@@ -15,6 +15,9 @@ depends: [
   "dyn" {= version}
   "odoc" {with-doc}
 ]
+conflicts: [
+  "ocaml-lsp-server" {< "1.15.0"}
+]
 dev-repo: "git+https://github.com/ocaml/dune.git"
 build: [
   ["dune" "subst"] {dev}
diff --git a/otherlibs/ocamlc_loc/src/lexer.mli b/otherlibs/ocamlc_loc/src/lexer.mli
index 757d2c592b4..02514550c7e 100644
--- a/otherlibs/ocamlc_loc/src/lexer.mli
+++ b/otherlibs/ocamlc_loc/src/lexer.mli
@@ -4,16 +4,18 @@ type lines =
   | Single of int
   | Range of int * int
 
+type code =
+  { code : int
+  ; name : string
+  }
+
 type source =
-  | Code of
-      { code : int
-      ; name : string
-      }
+  | Code of code
   | Alert of string
 
 type severity =
   | Error of source option
-  | Warning of source
+  | Warning of code
   | Alert of
       { name : string
       ; source : string
diff --git a/otherlibs/ocamlc_loc/src/lexer.mll b/otherlibs/ocamlc_loc/src/lexer.mll
index e614f577009..ed8c7913672 100644
--- a/otherlibs/ocamlc_loc/src/lexer.mll
+++ b/otherlibs/ocamlc_loc/src/lexer.mll
@@ -6,13 +6,18 @@
     | Single of int
     | Range of int * int
 
+  type code =
+    { code : int
+    ; name : string
+    }
+
   type source =
-    | Code of { code : int ; name : string }
+    | Code of code
     | Alert of string
 
   type severity =
     | Error of source option
-    | Warning of source
+    | Warning of code
     | Alert of { name : string ; source : string }
 
   type loc =
@@ -62,7 +67,7 @@ and severity = parse
     { Some (Error None, rest) }
   | "Warning" blank (digits as code) blank "[" ([^ ']']+ as name) "]:"
     (blank any as rest)
-    { Some (Warning (Code { code = int_of_string code ; name }), rest)
+    { Some (Warning { code = int_of_string code ; name }, rest)
     }
   | "Error" blank
     "(warning" blank (digits as code) blank "[" ([^ ']']+ as name) "]):"
@@ -74,11 +79,10 @@ and severity = parse
     }
   | (("Error" | "Warning") as kind) " (alert " ([^ ')']+ as alert) "):"
     (blank any as rest)
-    { let alert : source = Alert alert in
-      let res =
+    { let res =
         match kind with
-        | "Error" -> Error (Some alert)
-        | "Warning" -> Warning alert
+        | "Error" -> Error (Some (Alert alert))
+        | "Warning" -> Alert { name = alert ; source = "" }
         | _ -> assert false
       in
       Some (res, rest)
diff --git a/otherlibs/ocamlc_loc/src/ocamlc_loc.ml b/otherlibs/ocamlc_loc/src/ocamlc_loc.ml
index f6a555e24f0..48e2596a027 100644
--- a/otherlibs/ocamlc_loc/src/ocamlc_loc.ml
+++ b/otherlibs/ocamlc_loc/src/ocamlc_loc.ml
@@ -8,6 +8,10 @@ type report =
   ; related : (loc * string) list
   }
 
+let dyn_of_code { code; name } =
+  let open Dyn in
+  record [ ("code", int code); ("name", string name) ]
+
 let dyn_of_source =
   let open Dyn in
   function
@@ -18,7 +22,7 @@ let dyn_of_severity =
   let open Dyn in
   function
   | Error w -> variant "Error" [ option dyn_of_source w ]
-  | Warning w -> variant "Warning" [ dyn_of_source w ]
+  | Warning w -> variant "Warning" [ dyn_of_code w ]
   | Alert { name; source } ->
     variant "Alert"
       [ record [ ("name", string name); ("source", string source) ] ]
diff --git a/otherlibs/ocamlc_loc/src/ocamlc_loc.mli b/otherlibs/ocamlc_loc/src/ocamlc_loc.mli
index c98fad98e94..73c12936ad3 100644
--- a/otherlibs/ocamlc_loc/src/ocamlc_loc.mli
+++ b/otherlibs/ocamlc_loc/src/ocamlc_loc.mli
@@ -1,11 +1,13 @@
 [@@@alert
 unstable "The API of this library is not stable and may change without notice."]
 
+type code =
+  { code : int
+  ; name : string
+  }
+
 type source =
-  | Code of
-      { code : int
-      ; name : string
-      }
+  | Code of code
   | Alert of string
 
 type lines =
@@ -20,7 +22,7 @@ type loc =
 
 type severity =
   | Error of source option
-  | Warning of source
+  | Warning of code
   | Alert of
       { name : string
       ; source : string