diff --git a/lib/oven.py b/lib/oven.py
index af2b42f..3e6559b 100644
--- a/lib/oven.py
+++ b/lib/oven.py
@@ -217,13 +217,11 @@ class Oven(threading.Thread):
             # kiln too cold, wait for it to heat up
             if self.target - temp > config.kiln_must_catch_up_max_error:
                 log.info("kiln must catch up, too cold, shifting schedule")
-                self.start_time = self.start_time + \
-                    datetime.timedelta(seconds=self.time_step)
+                self.start_time = datetime.datetime.now() - datetime.timedelta(milliseconds = self.runtime * 1000)
             # kiln too hot, wait for it to cool down
             if temp - self.target > config.kiln_must_catch_up_max_error:
                 log.info("kiln must catch up, too hot, shifting schedule")
-                self.start_time = self.start_time + \
-                    datetime.timedelta(seconds=self.time_step)
+                self.start_time = datetime.datetime.now() - datetime.timedelta(milliseconds = self.runtime * 1000)
 
     def update_runtime(self):
         runtime_delta = datetime.datetime.now() - self.start_time