diff --git a/extmod/vfs_reader.c b/extmod/vfs_reader.c
index db13ce3c33..d3904c5c50 100644
--- a/extmod/vfs_reader.c
+++ b/extmod/vfs_reader.c
@@ -71,8 +71,11 @@ STATIC void mp_reader_vfs_close(void *data) {
 
 void mp_reader_new_file(mp_reader_t *reader, const char *filename) {
     mp_reader_vfs_t *rf = m_new_obj(mp_reader_vfs_t);
-    mp_obj_t arg = mp_obj_new_str(filename, strlen(filename));
-    rf->file = mp_vfs_open(1, &arg, (mp_map_t *)&mp_const_empty_map);
+    mp_obj_t args[2] = {
+        mp_obj_new_str(filename, strlen(filename)),
+        MP_OBJ_NEW_QSTR(MP_QSTR_rb),
+    };
+    rf->file = mp_vfs_open(MP_ARRAY_SIZE(args), &args[0], (mp_map_t *)&mp_const_empty_map);
     int errcode;
     rf->len = mp_stream_rw(rf->file, rf->buf, sizeof(rf->buf), &errcode, MP_STREAM_RW_READ | MP_STREAM_RW_ONCE);
     if (errcode != 0) {
diff --git a/tests/extmod/vfs_userfs.py b/tests/extmod/vfs_userfs.py
index 06e546b081..3cdfe82eea 100644
--- a/tests/extmod/vfs_userfs.py
+++ b/tests/extmod/vfs_userfs.py
@@ -16,14 +16,20 @@ except (ImportError, AttributeError):
 
 
 class UserFile(uio.IOBase):
-    def __init__(self, data):
+    def __init__(self, mode, data):
+        assert isinstance(data, bytes)
+        self.is_text = mode.find("b") == -1
         self.data = data
         self.pos = 0
 
     def read(self):
-        return self.data
+        if self.is_text:
+            return str(self.data, "utf8")
+        else:
+            return self.data
 
     def readinto(self, buf):
+        assert not self.is_text
         n = 0
         while n < len(buf) and self.pos < len(self.data):
             buf[n] = self.data[self.pos]
@@ -54,12 +60,12 @@ class UserFS:
 
     def open(self, path, mode):
         print("open", path, mode)
-        return UserFile(self.files[path])
+        return UserFile(mode, self.files[path])
 
 
 # create and mount a user filesystem
 user_files = {
-    "/data.txt": b"some data in a text file\n",
+    "/data.txt": b"some data in a text file",
     "/usermod1.py": b"print('in usermod1')\nimport usermod2",
     "/usermod2.py": b"print('in usermod2')",
 }
diff --git a/tests/extmod/vfs_userfs.py.exp b/tests/extmod/vfs_userfs.py.exp
index 6a4d925b91..00ddd95fca 100644
--- a/tests/extmod/vfs_userfs.py.exp
+++ b/tests/extmod/vfs_userfs.py.exp
@@ -1,12 +1,12 @@
 open /data.txt r
-b'some data in a text file\n'
+some data in a text file
 stat /usermod1
 stat /usermod1.py
-open /usermod1.py r
+open /usermod1.py rb
 ioctl 4 0
 in usermod1
 stat /usermod2
 stat /usermod2.py
-open /usermod2.py r
+open /usermod2.py rb
 ioctl 4 0
 in usermod2