diff --git a/builder-web.opam b/builder-web.opam
index 5dfd9a0..7cb1b27 100644
--- a/builder-web.opam
+++ b/builder-web.opam
@@ -53,6 +53,8 @@ depends: [
   "alcotest" {with-test}
   "ppx_deriving" {with-test}
   "ppx_deriving_yojson" {with-test}
+  "conan-unix" {>= "0.0.2"}
+  "conan-database" {>= "0.0.2"}
 ]
 
 synopsis: "Web interface for builder"
diff --git a/lib/builder_web.ml b/lib/builder_web.ml
index 5ed367b..4b3c359 100644
--- a/lib/builder_web.ml
+++ b/lib/builder_web.ml
@@ -60,12 +60,16 @@ let mime_lookup path =
     (match Fpath.to_string path with
      | "build-environment" | "opam-switch" | "system-packages" ->
        "text/plain"
-     | _ ->
+     | filename ->
        if Fpath.has_ext "build-hashes" path
        then "text/plain"
        else if Fpath.is_prefix Fpath.(v "bin/") path
        then "application/octet-stream"
-       else Magic_mime.lookup (Fpath.to_string path))
+       else match Option.bind
+                    (Result.to_option (Conan_unix.run_with_tree Conan_magic_database.tree filename))
+                    Conan.Metadata.mime with
+       | Some mime_type -> mime_type
+       | None -> "application/octet-stream" (* default *))
 
 let string_of_html =
   Format.asprintf "%a" (Tyxml.Html.pp ())
diff --git a/lib/dune b/lib/dune
index c0fab85..9f1e659 100644
--- a/lib/dune
+++ b/lib/dune
@@ -18,4 +18,6 @@
   decompress.de
   decompress.gz
   uri
+  conan-unix
+  conan-database
   ))