diff --git a/src/Tiny_httpd_dir.ml b/src/Tiny_httpd_dir.ml
index 91183660..94b63399 100644
--- a/src/Tiny_httpd_dir.ml
+++ b/src/Tiny_httpd_dir.ml
@@ -82,8 +82,8 @@ let vfs_of_dir (top:string) : vfs =
     let contains f = Sys.file_exists (top // f)
     let list_dir f = Sys.readdir (top // f)
     let read_file_content f =
-      let ic = open_in_bin (top // f) in
-      Tiny_httpd_stream.of_chan ic
+      let ic = Unix.(openfile (top // f) [O_RDONLY] 0) in
+      Tiny_httpd_stream.of_fd ic
     let create f =
       let oc = open_out_bin (top // f) in
       let write = output oc in
@@ -398,4 +398,3 @@ module Embedded_fs = struct
     end in (module M)
 
 end
-
diff --git a/src/Tiny_httpd_stream.ml b/src/Tiny_httpd_stream.ml
index 2b12ab02..9490e016 100644
--- a/src/Tiny_httpd_stream.ml
+++ b/src/Tiny_httpd_stream.ml
@@ -120,13 +120,13 @@ let of_string s : t =
   of_bytes (Bytes.unsafe_of_string s)
 
 let with_file ?buf_size file f =
-  let ic = open_in file in
+  let ic = Unix.(openfile file [O_RDONLY] 0) in
   try
-    let x = f (of_chan ?buf_size ic) in
-    close_in ic;
+    let x = f (of_fd ?buf_size ic) in
+    Unix.close ic;
     x
   with e ->
-    close_in_noerr ic;
+    Unix.close ic;
     raise e
 
 let read_all ?(buf=Buf.create()) (self:t) : string =