diff --git a/google/cloud/storage/notification.py b/google/cloud/storage/notification.py
index 4eb807fa9..9af476d58 100644
--- a/google/cloud/storage/notification.py
+++ b/google/cloud/storage/notification.py
@@ -255,7 +255,7 @@ def create(self, client=None, timeout=_DEFAULT_TIMEOUT, retry=None):
         """
         if self.notification_id is not None:
             raise ValueError(
-                f"Notification already exists w/ id: {self.notification_id}"
+                f"notification_id already set to {self.notification_id}; must be None to create a Notification."
             )
 
         client = self._require_client(client)