diff --git a/src/NodaTimeSplitter.php b/src/NodaTimeSplitter.php
index 72d52ac..f5b1ee1 100644
--- a/src/NodaTimeSplitter.php
+++ b/src/NodaTimeSplitter.php
@@ -1030,8 +1030,9 @@ final class NodaTimeSplitter {
 
         $middle_substraction = round($days_diff / 2);
 
-        $middle_day = date('Y-m-d',
-            strtotime('+' . $middle_substraction . ' days', strtotime($startDate->format('Y-m-d'))));
+        if (!($startDateTimestamp = strtotime($startDate->format('Y-m-d')))) return [];
+        if (!($middleDayTimestamp = strtotime('+' . $middle_substraction . ' days', $startDateTimestamp))) return [];
+        $middle_day = date('Y-m-d', $middleDayTimestamp);
 
         $start_name = self::timePartsToTimeName($start);
         $end_name = self::timePartsToTimeName($end);