diff --git a/djangoldp_webpushnotification/models.py b/djangoldp_webpushnotification/models.py
index 32788cd..87b62c8 100644
--- a/djangoldp_webpushnotification/models.py
+++ b/djangoldp_webpushnotification/models.py
@@ -14,7 +14,7 @@ class VAPIDKeyset(models.Model):
 
     @property
     def public_key(self):
-        key_str = self.private_key
+        key_str = self.private_key.tobytes()
         padding = len(key_str) % 4
         key_str += b"=" * padding
         key = SigningKey.from_string(