diff --git a/collector/expect_test_collector.ml b/collector/expect_test_collector.ml
index f1bdb91..482fe81 100644
--- a/collector/expect_test_collector.ml
+++ b/collector/expect_test_collector.ml
@@ -101,7 +101,7 @@ module Make (C : Expect_test_config_types.S) = struct
 
     let create () =
       let filename = Filename.temp_file "expect-test" "output" in
-      let chan = open_out filename in
+      let chan = open_out_bin filename in
       before_test ~output:chan ~stdout ~stderr;
       { chan; filename = File.Name.of_string filename; saved = [] }
     ;;
@@ -120,7 +120,7 @@ module Make (C : Expect_test_config_types.S) = struct
     let relative_filename t = File.Name.relative_to ~dir:(File.initial_dir ()) t.filename
 
     let with_ic fname ~f =
-      let ic = open_in fname in
+      let ic = open_in_bin fname in
       protect ~finally:(fun () -> close_in ic) ~f:(fun () -> f ic)
     ;;