diff --git a/ErsatzTV.Application/Scheduling/Commands/ReplaceDecoTemplateItemsHandler.cs b/ErsatzTV.Application/Scheduling/Commands/ReplaceDecoTemplateItemsHandler.cs
index 7d67f1364..42035aaa2 100644
--- a/ErsatzTV.Application/Scheduling/Commands/ReplaceDecoTemplateItemsHandler.cs
+++ b/ErsatzTV.Application/Scheduling/Commands/ReplaceDecoTemplateItemsHandler.cs
@@ -99,6 +99,13 @@ public class ReplaceDecoTemplateItemsHandler(IDbContextFactory<TvContext> dbCont
 
         foreach (DecoTemplateItemRange item in itemsWithEffectiveEnd)
         {
+            if (item.StartTime < TimeSpan.Zero || item.StartTime >= TimeSpan.FromHours(24) ||
+                item.EndTime < TimeSpan.Zero || item.EndTime > TimeSpan.FromHours(24))
+            {
+                return BaseError.New(
+                    $"Deco from {item.StartTime} to {item.EndTime} must be within a single day (00:00 to 24:00)");
+            }
+
             if (item.StartTime >= item.EffectiveEndTime)
             {
                 return BaseError.New(