diff --git a/hc/api/models.py b/hc/api/models.py
index 17d422fe..ee702b8f 100644
--- a/hc/api/models.py
+++ b/hc/api/models.py
@@ -97,7 +97,7 @@ class Check(models.Model):
         """ Return the datetime when grace period starts. """
 
         # The common case, grace starts after timeout
-        if not self.schedule:
+        if self.kind == "simple":
             return self.last_ping + self.timeout
 
         # The complex case, next ping is expected based on cron schedule
diff --git a/hc/api/tests/test_check_model.py b/hc/api/tests/test_check_model.py
index 6eb0b736..ad347558 100644
--- a/hc/api/tests/test_check_model.py
+++ b/hc/api/tests/test_check_model.py
@@ -43,7 +43,7 @@ class CheckModelTestCase(TestCase):
 
         # Expect ping every midnight, default grace is 1 hour
         check = Check()
-        check.timeout = timedelta(minutes=0)
+        check.kind = "cron"
         check.schedule = "0 0 * * *"
         check.status = "up"
         check.last_ping = dt
@@ -61,7 +61,7 @@ class CheckModelTestCase(TestCase):
 
         # Expect ping every day at 10am, default grace is 1 hour
         check = Check()
-        check.timeout = timedelta(minutes=0)
+        check.kind = "cron"
         check.schedule = "0 10 * * *"
         check.status = "up"
         check.last_ping = dt