diff --git a/calendar/api_event.go b/calendar/api_event.go
index 4464d69..629d994 100644
--- a/calendar/api_event.go
+++ b/calendar/api_event.go
@@ -62,7 +62,7 @@ func ApiEventNew(c *gin.Context) {
 	if e.ID != "" {
 		panic(errors.ErrorBadRequest)
 	}
-	if e.Start.IsZero() || e.End.IsZero() || e.Start.Before(e.End) {
+	if e.Start.IsZero() || e.End.IsZero() || e.End.Before(e.Start) {
 		panic(ErrorInvalidTime)
 	}
 	cal := 0