diff --git a/hc/api/models.py b/hc/api/models.py
index b27f352d..98aca553 100644
--- a/hc/api/models.py
+++ b/hc/api/models.py
@@ -116,7 +116,7 @@ class Check(models.Model):
         return str(self.code)
 
     def relative_url(self):
-        if self.project.show_slugs:
+        if self.project_id and self.project.show_slugs:
             if not self.slug:
                 return None
 
@@ -267,7 +267,7 @@ class Check(models.Model):
             update_rel_url = reverse("hc-api-single", args=[self.code])
             pause_rel_url = reverse("hc-api-pause", args=[self.code])
 
-            result["ping_url"] = self.url()
+            result["ping_url"] = settings.PING_ENDPOINT + str(self.code)
             result["update_url"] = settings.SITE_ROOT + update_rel_url
             result["pause_url"] = settings.SITE_ROOT + pause_rel_url
             result["channels"] = self.channels_str()