diff --git a/extmod/vfs_fat_lexer.c b/extmod/vfs_fat_lexer.c
new file mode 100644
index 0000000000..c99ca9e264
--- /dev/null
+++ b/extmod/vfs_fat_lexer.c
@@ -0,0 +1,76 @@
+/*
+ * This file is part of the Micro Python project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2013, 2014 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdio.h>
+
+#include "py/lexer.h"
+#include "lib/fatfs/ff.h"
+
+typedef struct _mp_lexer_file_buf_t {
+    FIL fp;
+    byte buf[20];
+    uint16_t len;
+    uint16_t pos;
+} mp_lexer_file_buf_t;
+
+STATIC mp_uint_t file_buf_next_byte(mp_lexer_file_buf_t *fb) {
+    if (fb->pos >= fb->len) {
+        if (fb->len < sizeof(fb->buf)) {
+            return MP_LEXER_EOF;
+        } else {
+            UINT n;
+            f_read(&fb->fp, fb->buf, sizeof(fb->buf), &n);
+            if (n == 0) {
+                return MP_LEXER_EOF;
+            }
+            fb->len = n;
+            fb->pos = 0;
+        }
+    }
+    return fb->buf[fb->pos++];
+}
+
+STATIC void file_buf_close(mp_lexer_file_buf_t *fb) {
+    f_close(&fb->fp);
+    m_del_obj(mp_lexer_file_buf_t, fb);
+}
+
+mp_lexer_t *fat_vfs_lexer_new_from_file(const char *filename) {
+    mp_lexer_file_buf_t *fb = m_new_obj_maybe(mp_lexer_file_buf_t);
+    if (fb == NULL) {
+        return NULL;
+    }
+    FRESULT res = f_open(&fb->fp, filename, FA_READ);
+    if (res != FR_OK) {
+        m_del_obj(mp_lexer_file_buf_t, fb);
+        return NULL;
+    }
+    UINT n;
+    f_read(&fb->fp, fb->buf, sizeof(fb->buf), &n);
+    fb->len = n;
+    fb->pos = 0;
+    return mp_lexer_new(qstr_from_str(filename), fb, (mp_lexer_stream_next_byte_t)file_buf_next_byte, (mp_lexer_stream_close_t)file_buf_close);
+}
diff --git a/py/py.mk b/py/py.mk
index 9cf731b99f..1c746c923f 100644
--- a/py/py.mk
+++ b/py/py.mk
@@ -174,6 +174,7 @@ PY_O_BASENAME = \
 	../extmod/vfs_fat_ffconf.o \
 	../extmod/vfs_fat_diskio.o \
 	../extmod/vfs_fat_file.o \
+	../extmod/vfs_fat_lexer.o \
 	../extmod/vfs_fat_misc.o \
 	../extmod/moduos_dupterm.o \
 
diff --git a/stmhal/lexerfatfs.c b/stmhal/lexerfatfs.c
index 39b8fefa92..fd7f62dfdd 100644
--- a/stmhal/lexerfatfs.c
+++ b/stmhal/lexerfatfs.c
@@ -1,5 +1,5 @@
 /*
- * This file is part of the Micro Python project, http://micropython.org/
+ * This file is part of the MicroPython project, http://micropython.org/
  *
  * The MIT License (MIT)
  *
@@ -24,53 +24,12 @@
  * THE SOFTWARE.
  */
 
-#include <stdio.h>
-
 #include "py/lexer.h"
-#include "lib/fatfs/ff.h"
 
-typedef struct _mp_lexer_file_buf_t {
-    FIL fp;
-    byte buf[20];
-    uint16_t len;
-    uint16_t pos;
-} mp_lexer_file_buf_t;
-
-STATIC mp_uint_t file_buf_next_byte(mp_lexer_file_buf_t *fb) {
-    if (fb->pos >= fb->len) {
-        if (fb->len < sizeof(fb->buf)) {
-            return MP_LEXER_EOF;
-        } else {
-            UINT n;
-            f_read(&fb->fp, fb->buf, sizeof(fb->buf), &n);
-            if (n == 0) {
-                return MP_LEXER_EOF;
-            }
-            fb->len = n;
-            fb->pos = 0;
-        }
-    }
-    return fb->buf[fb->pos++];
-}
-
-STATIC void file_buf_close(mp_lexer_file_buf_t *fb) {
-    f_close(&fb->fp);
-    m_del_obj(mp_lexer_file_buf_t, fb);
-}
+mp_lexer_t *fat_vfs_lexer_new_from_file(const char *filename);
 
+// TODO: Instead of such shims, probably better to let port #define
+// mp_lexer_new_from_file to a function it wants to use.
 mp_lexer_t *mp_lexer_new_from_file(const char *filename) {
-    mp_lexer_file_buf_t *fb = m_new_obj_maybe(mp_lexer_file_buf_t);
-    if (fb == NULL) {
-        return NULL;
-    }
-    FRESULT res = f_open(&fb->fp, filename, FA_READ);
-    if (res != FR_OK) {
-        m_del_obj(mp_lexer_file_buf_t, fb);
-        return NULL;
-    }
-    UINT n;
-    f_read(&fb->fp, fb->buf, sizeof(fb->buf), &n);
-    fb->len = n;
-    fb->pos = 0;
-    return mp_lexer_new(qstr_from_str(filename), fb, (mp_lexer_stream_next_byte_t)file_buf_next_byte, (mp_lexer_stream_close_t)file_buf_close);
+    return fat_vfs_lexer_new_from_file(filename);
 }