diff --git a/invenio_theme_tugraz/views.py b/invenio_theme_tugraz/views.py
index d15c692..c847035 100644
--- a/invenio_theme_tugraz/views.py
+++ b/invenio_theme_tugraz/views.py
@@ -105,7 +105,7 @@ def retrieve_doi():
 
     doi_response = requests.post(
         url,
-        auth=(username, password),
+        auth=(username, password.encode('utf-8')),
         json=doi_metadata,
     )