diff --git a/ocaml-lsp-server/src/workspace_symbol.ml b/ocaml-lsp-server/src/workspace_symbol.ml
index 2f0ef9a6a..dbdab220b 100644
--- a/ocaml-lsp-server/src/workspace_symbol.ml
+++ b/ocaml-lsp-server/src/workspace_symbol.ml
@@ -205,8 +205,8 @@ end
 
 exception Cancelled
 
-let symbols_from_cm_file ~filter root_uri (cancel : Fiber.Cancel.t option)
-    cm_file =
+let symbols_from_cm_file ~build_dir ~filter root_uri
+    (cancel : Fiber.Cancel.t option) cm_file =
   let cmt =
     let filename = string_of_cm cm_file in
     let cancelled =
@@ -230,7 +230,14 @@ let symbols_from_cm_file ~filter root_uri (cancel : Fiber.Cancel.t option)
         in
         let loc = Mbrowse.node_loc browse in
         let fname = loc.loc_start.pos_fname in
-        let uri = Uri.of_path (Filename.concat root_uri fname) in
+        let uri =
+          let sourcefile = Filename.concat root_uri fname in
+          let path =
+            if Fpath.exists (Fpath.of_string sourcefile) then sourcefile
+            else build_dir ^ "/" ^ fname
+          in
+          Uri.of_path path
+        in
         filter (Document_symbol.symbols_of_outline uri outline))
     | _ -> [])
 
@@ -288,7 +295,7 @@ let run ({ query; _ } : WorkspaceSymbolParams.t)
              Uri.to_path uri
            in
            List.concat_map
-             ~f:(symbols_from_cm_file ~filter path cancel)
+             ~f:(symbols_from_cm_file ~build_dir ~filter path cancel)
              cm_files))
   with Cancelled -> Error `Cancelled
 
diff --git a/ocaml-lsp-server/test/e2e/__tests__/workspace-symbol.test.ts b/ocaml-lsp-server/test/e2e/__tests__/workspace-symbol.test.ts
index 7d77fa570..9d86f1016 100644
--- a/ocaml-lsp-server/test/e2e/__tests__/workspace-symbol.test.ts
+++ b/ocaml-lsp-server/test/e2e/__tests__/workspace-symbol.test.ts
@@ -120,6 +120,7 @@ describe("workspace/symbol", () => {
         "lib_x 12 /workspace_symbol_A/lib/lib.ml 6:0 6:14",
         "user 15 /workspace_symbol_A/lib/lib.ml 3:0 5:1",
         "name 7 /workspace_symbol_A/lib/lib.ml 4:2 4:14",
+        "hello 12 /workspace_symbol_A/_build/default/lib/gen.ml 0:0 0:19",
         "t 15 /workspace_symbol_A/lib/LibTypes.mli 0:0 0:15",
         "x 12 /workspace_symbol_A/vendor/vendored_lib.ml 0:0 0:9",
       ]
@@ -200,6 +201,7 @@ describe("workspace/symbol", () => {
         "lib_x 12 /workspace_symbol_A/lib/lib.ml 6:0 6:14",
         "user 15 /workspace_symbol_A/lib/lib.ml 3:0 5:1",
         "name 7 /workspace_symbol_A/lib/lib.ml 4:2 4:14",
+        "hello 12 /workspace_symbol_A/_build/default/lib/gen.ml 0:0 0:19",
         "t 15 /workspace_symbol_A/lib/LibTypes.mli 0:0 0:15",
         "x 12 /workspace_symbol_A/vendor/vendored_lib.ml 0:0 0:9",
         "workspace_B 12 /workspace_symbol_B/main.ml 0:0 0:31",
diff --git a/ocaml-lsp-server/test/e2e/__tests__/workspace_symbol_A/lib/dune b/ocaml-lsp-server/test/e2e/__tests__/workspace_symbol_A/lib/dune
index 0b5c5e2bc..b97308520 100644
--- a/ocaml-lsp-server/test/e2e/__tests__/workspace_symbol_A/lib/dune
+++ b/ocaml-lsp-server/test/e2e/__tests__/workspace_symbol_A/lib/dune
@@ -4,5 +4,11 @@
  (flags :standard -w -32-38-27-34)
  (name lib))
 
-
 (copy_files# ../vendor/*.ml{,i})
+
+(rule
+ (target gen.ml)
+ (action
+  (with-stdout-to
+   %{target}
+   (echo "let hello = \"world\""))))