diff --git a/date/date_c.php b/date/date_c.php
index 3ec4cda37..8da12b1ec 100644
--- a/date/date_c.php
+++ b/date/date_c.php
@@ -299,6 +299,7 @@ public static function getLastErrors(): array|false {}
     #[Pure]
     #[TentativeType]
     #[LanguageLevelTypeAware(['8.4' => 'DateTimeImmutable'], default: 'static|false')]
+    #[\NoDiscard(message: "as DateTimeImmutable::modify() does not modify the object itself")]
     public function modify(#[LanguageLevelTypeAware(['8.0' => 'string'], default: '')] $modifier) {}
 
     /**
@@ -706,6 +707,7 @@ public function modify(#[LanguageLevelTypeAware(['8.0' => 'string'], default: ''
      * @link https://php.net/manual/en/datetime.add.php
      */
     #[TentativeType]
+    #[\NoDiscard(message: "as DateTimeImmutable::add() does not modify the object itself")]
     public function add(DateInterval $interval): DateTime {}
 
     /**
@@ -725,6 +727,7 @@ public static function createFromImmutable(DateTimeImmutable $object) {}
      * @throws DateInvalidOperationException
      */
     #[TentativeType]
+    #[\NoDiscard(message: "as DateTimeImmutable::sub() does not modify the object itself")]
     public function sub(DateInterval $interval): DateTime {}
 
     /**
@@ -742,6 +745,7 @@ public function getTimezone(): DateTimeZone|false {}
      * @link https://php.net/manual/en/datetime.settimezone.php
      */
     #[TentativeType]
+    #[\NoDiscard(message: "as DateTimeImmutable::setTimezone() does not modify the object itself")]
     public function setTimezone(#[LanguageLevelTypeAware(['8.0' => 'DateTimeZone'], default: '')] $timezone): DateTime {}
 
     /**
@@ -762,6 +766,7 @@ public function getOffset(): int {}
      * @link https://php.net/manual/en/datetime.settime.php
      */
     #[TentativeType]
+    #[\NoDiscard(message: "as DateTimeImmutable::setTime() does not modify the object itself")]
     public function setTime(
         #[LanguageLevelTypeAware(['8.0' => 'int'], default: '')] $hour,
         #[LanguageLevelTypeAware(['8.0' => 'int'], default: '')] $minute,
@@ -778,6 +783,7 @@ public function setTime(
      * @link https://php.net/manual/en/datetime.setdate.php
      */
     #[TentativeType]
+    #[\NoDiscard(message: "as DateTimeImmutable::setDate() does not modify the object itself")]
     public function setDate(
         #[LanguageLevelTypeAware(['8.0' => 'int'], default: '')] $year,
         #[LanguageLevelTypeAware(['8.0' => 'int'], default: '')] $month,
@@ -793,6 +799,7 @@ public function setDate(
      * @link https://php.net/manual/en/datetime.setisodate.php
      */
     #[TentativeType]
+    #[\NoDiscard(message: "as DateTimeImmutable::setISODate() does not modify the object itself")]
     public function setISODate(
         #[LanguageLevelTypeAware(['8.0' => 'int'], default: '')] $year,
         #[LanguageLevelTypeAware(['8.0' => 'int'], default: '')] $week,
@@ -806,6 +813,7 @@ public function setISODate(
      * @link https://php.net/manual/en/datetime.settimestamp.php
      */
     #[TentativeType]
+    #[\NoDiscard(message: "as DateTimeImmutable::setTimestamp() does not modify the object itself")]
     public function setTimestamp(#[LanguageLevelTypeAware(['8.0' => 'int'], default: '')] $timestamp): DateTime {}
 
     /**
@@ -906,6 +914,7 @@ public function getMicrosecond(): int {}
     /**
      * @since 8.4
      */
+    #[\NoDiscard(message: "as DateTimeImmutable::setMicrosecond() does not modify the object itself")]
     public function setMicrosecond(int $microsecond): static {}
 }