diff --git a/backend/users/models.py b/backend/users/models.py
index d0275cdf..99da7f37 100644
--- a/backend/users/models.py
+++ b/backend/users/models.py
@@ -129,7 +129,7 @@ def old_hash_password(self, password, method, salt=None, pepper=None):
             return None
 
         if salt:
-            h = hmac.new(salt, password, method)
+            h = hmac.new(salt.encode("utf8"), password.encode("utf8"), method)
         else:
             h = method(password)