diff --git a/lms/tools.py b/lms/tools.py
index 8c258cd..32f0002 100644
--- a/lms/tools.py
+++ b/lms/tools.py
@@ -12,7 +12,7 @@ def decode_base64(my_str, upload_to=None):
         path = "%s/%s" % (settings.MEDIA_ROOT, upload_to)
         os.makedirs(os.path.dirname(path), exist_ok=True)
         url = "%s%s" % (settings.MEDIA_URL, upload_to)
-        with open(path, "w") as fh:
+        with open(path, "wb") as fh:
             fh.write(base64.b64decode(my_str))
         return url
     return my_str