diff --git a/opium.opam b/opium.opam
index c9b08c70..2fdb7099 100644
--- a/opium.opam
+++ b/opium.opam
@@ -25,6 +25,7 @@ depends: [
   "ppx_sexp_conv" {>= "v0.9.0"}
   "re" {>= "1.3.0"}
   "magic-mime"
+  "stringext"
   "alcotest" {test}
   "cow" {test & >= "0.10.0"}
 ]
diff --git a/opium/jbuild b/opium/jbuild
index 78892ab3..3f1e810c 100644
--- a/opium/jbuild
+++ b/opium/jbuild
@@ -11,4 +11,5 @@
     cmdliner
     cohttp-lwt-unix
     magic-mime
-    logs))))
+    logs
+    stringext))))
diff --git a/opium/static_serve.ml b/opium/static_serve.ml
index 3966651c..d87acdd0 100644
--- a/opium/static_serve.ml
+++ b/opium/static_serve.ml
@@ -35,7 +35,7 @@ let public_serve t ~requested ~request_if_none_match ?etag_of_fname ?headers ()
       match request_if_none_match, etag_quoted with
       | Some request_etags, Some etag_quoted ->
         request_etags
-        |> String.split_on_char ','
+        |> Stringext.split ~on:','
         |> List.exists ~f:(fun request_etag ->
           String.trim request_etag = etag_quoted
         )