diff --git a/plugins/OStatus/actions/usersalmon.php b/plugins/OStatus/actions/usersalmon.php
index ca0370bb4e..8368eeccf0 100644
--- a/plugins/OStatus/actions/usersalmon.php
+++ b/plugins/OStatus/actions/usersalmon.php
@@ -88,6 +88,12 @@ class UsersalmonAction extends SalmonAction
             throw new ClientException("Not to anyone in reply to anything!");
         }
 
+        $existing = Notice::staticGet('uri', $this->act->object->id);
+
+        if (!empty($existing)) {
+            common_log(LOG_ERR, "Not saving notice '{$existing->uri}'; already exists.");
+        }
+
         $this->saveNotice();
     }