diff --git a/src/flask_httpauth.py b/src/flask_httpauth.py
index 146da9a..55fd195 100644
--- a/src/flask_httpauth.py
+++ b/src/flask_httpauth.py
@@ -224,10 +224,12 @@ def get_auth(self):
         except (ValueError, TypeError):
             return None
         try:
+            scheme = scheme.decode('utf-8')
             username = encoded_username.decode('utf-8')
             password = encoded_password.decode('utf-8')
         except UnicodeDecodeError:
             # try to decode again with latin-1, which should always work
+            scheme = scheme.decode('latin1')
             username = encoded_username.decode('latin1')
             password = encoded_password.decode('latin1')