diff --git a/modules/zividsamples/gui/preparation/warmup_gui.py b/modules/zividsamples/gui/preparation/warmup_gui.py
index 0a11d001..2ed494cb 100644
--- a/modules/zividsamples/gui/preparation/warmup_gui.py
+++ b/modules/zividsamples/gui/preparation/warmup_gui.py
@@ -306,7 +306,7 @@ def temperature_is_stable(self) -> bool:
 
         one_minute_ago = now - timedelta(minutes=1)
         last_minute_of_data = self.df[self.df["timestamp"] >= one_minute_ago]
-        max_rate_of_change_in_the_last_minute = float(last_minute_of_data["average_rate_of_change"].max())
+        max_rate_of_change_in_the_last_minute = float(np.asarray(last_minute_of_data["average_rate_of_change"]).max())
 
         return (
             self.df["average_rate_of_change"].iloc[-1] is not None