diff --git a/generated/8.4/datetime.php b/generated/8.4/datetime.php
index dcc815cc..9a3e6f8d 100644
--- a/generated/8.4/datetime.php
+++ b/generated/8.4/datetime.php
@@ -545,11 +545,12 @@ function date(string $format, ?int $timestamp = null): string
  * Values less than 1 (including negative values) reference the days in the previous month, so 0 is the last day of the previous month, -1 is the day before that, etc.
  * Values greater than the number of days in the relevant month reference the appropriate day in the following month(s).
  * @param int|null $year The year
- * @return false|int Returns a int Unix timestamp on success, or FALSE if the
+ * @return int Returns a int Unix timestamp on success, or FALSE if the
  * timestamp doesn't fit in a PHP integer.
+ * @throws DatetimeException
  *
  */
-function gmmktime(int $hour, ?int $minute = null, ?int $second = null, ?int $month = null, ?int $day = null, ?int $year = null)
+function gmmktime(int $hour, ?int $minute = null, ?int $second = null, ?int $month = null, ?int $day = null, ?int $year = null): int
 {
     error_clear_last();
     if ($year !== null) {
@@ -565,6 +566,9 @@ function gmmktime(int $hour, ?int $minute = null, ?int $second = null, ?int $mon
     } else {
         $safeResult = \gmmktime($hour);
     }
+    if ($safeResult === false) {
+        throw DatetimeException::createFromPhpError();
+    }
     return $safeResult;
 }
 
@@ -769,11 +773,12 @@ function idate(string $format, ?int $timestamp = null): int
  * 1970-2000. On systems where time_t is a 32bit signed integer, as
  * most common today, the valid range for year
  * is somewhere between 1901 and 2038.
- * @return false|int mktime returns the Unix timestamp of the arguments
+ * @return int mktime returns the Unix timestamp of the arguments
  * given, or FALSE if the timestamp doesn't fit in a PHP integer.
+ * @throws DatetimeException
  *
  */
-function mktime(int $hour, ?int $minute = null, ?int $second = null, ?int $month = null, ?int $day = null, ?int $year = null)
+function mktime(int $hour, ?int $minute = null, ?int $second = null, ?int $month = null, ?int $day = null, ?int $year = null): int
 {
     error_clear_last();
     if ($year !== null) {
@@ -789,6 +794,9 @@ function mktime(int $hour, ?int $minute = null, ?int $second = null, ?int $month
     } else {
         $safeResult = \mktime($hour);
     }
+    if ($safeResult === false) {
+        throw DatetimeException::createFromPhpError();
+    }
     return $safeResult;
 }
 
diff --git a/generated/8.4/functionsList.php b/generated/8.4/functionsList.php
index 5d81d3a4..2b371b9f 100644
--- a/generated/8.4/functionsList.php
+++ b/generated/8.4/functionsList.php
@@ -243,6 +243,7 @@
     'get_include_path',
     'get_meta_tags',
     'glob',
+    'gmmktime',
     'gmstrftime',
     'gnupg_adddecryptkey',
     'gnupg_addencryptkey',
@@ -506,6 +507,7 @@
     'md5_file',
     'mime_content_type',
     'mkdir',
+    'mktime',
     'msg_get_queue',
     'msg_queue_exists',
     'msg_receive',
diff --git a/generated/8.4/rector-migrate.php b/generated/8.4/rector-migrate.php
index 690f9938..c497c581 100644
--- a/generated/8.4/rector-migrate.php
+++ b/generated/8.4/rector-migrate.php
@@ -251,6 +251,7 @@
             'get_include_path' => 'Safe\get_include_path',
             'get_meta_tags' => 'Safe\get_meta_tags',
             'glob' => 'Safe\glob',
+            'gmmktime' => 'Safe\gmmktime',
             'gmstrftime' => 'Safe\gmstrftime',
             'gnupg_adddecryptkey' => 'Safe\gnupg_adddecryptkey',
             'gnupg_addencryptkey' => 'Safe\gnupg_addencryptkey',
@@ -514,6 +515,7 @@
             'md5_file' => 'Safe\md5_file',
             'mime_content_type' => 'Safe\mime_content_type',
             'mkdir' => 'Safe\mkdir',
+            'mktime' => 'Safe\mktime',
             'msg_get_queue' => 'Safe\msg_get_queue',
             'msg_queue_exists' => 'Safe\msg_queue_exists',
             'msg_receive' => 'Safe\msg_receive',
diff --git a/generated/8.5/datetime.php b/generated/8.5/datetime.php
index dcc815cc..9a3e6f8d 100644
--- a/generated/8.5/datetime.php
+++ b/generated/8.5/datetime.php
@@ -545,11 +545,12 @@ function date(string $format, ?int $timestamp = null): string
  * Values less than 1 (including negative values) reference the days in the previous month, so 0 is the last day of the previous month, -1 is the day before that, etc.
  * Values greater than the number of days in the relevant month reference the appropriate day in the following month(s).
  * @param int|null $year The year
- * @return false|int Returns a int Unix timestamp on success, or FALSE if the
+ * @return int Returns a int Unix timestamp on success, or FALSE if the
  * timestamp doesn't fit in a PHP integer.
+ * @throws DatetimeException
  *
  */
-function gmmktime(int $hour, ?int $minute = null, ?int $second = null, ?int $month = null, ?int $day = null, ?int $year = null)
+function gmmktime(int $hour, ?int $minute = null, ?int $second = null, ?int $month = null, ?int $day = null, ?int $year = null): int
 {
     error_clear_last();
     if ($year !== null) {
@@ -565,6 +566,9 @@ function gmmktime(int $hour, ?int $minute = null, ?int $second = null, ?int $mon
     } else {
         $safeResult = \gmmktime($hour);
     }
+    if ($safeResult === false) {
+        throw DatetimeException::createFromPhpError();
+    }
     return $safeResult;
 }
 
@@ -769,11 +773,12 @@ function idate(string $format, ?int $timestamp = null): int
  * 1970-2000. On systems where time_t is a 32bit signed integer, as
  * most common today, the valid range for year
  * is somewhere between 1901 and 2038.
- * @return false|int mktime returns the Unix timestamp of the arguments
+ * @return int mktime returns the Unix timestamp of the arguments
  * given, or FALSE if the timestamp doesn't fit in a PHP integer.
+ * @throws DatetimeException
  *
  */
-function mktime(int $hour, ?int $minute = null, ?int $second = null, ?int $month = null, ?int $day = null, ?int $year = null)
+function mktime(int $hour, ?int $minute = null, ?int $second = null, ?int $month = null, ?int $day = null, ?int $year = null): int
 {
     error_clear_last();
     if ($year !== null) {
@@ -789,6 +794,9 @@ function mktime(int $hour, ?int $minute = null, ?int $second = null, ?int $month
     } else {
         $safeResult = \mktime($hour);
     }
+    if ($safeResult === false) {
+        throw DatetimeException::createFromPhpError();
+    }
     return $safeResult;
 }
 
diff --git a/generated/8.5/functionsList.php b/generated/8.5/functionsList.php
index 974fa412..5b38e8b5 100644
--- a/generated/8.5/functionsList.php
+++ b/generated/8.5/functionsList.php
@@ -243,6 +243,7 @@
     'get_include_path',
     'get_meta_tags',
     'glob',
+    'gmmktime',
     'gmstrftime',
     'gnupg_adddecryptkey',
     'gnupg_addencryptkey',
@@ -506,6 +507,7 @@
     'md5_file',
     'mime_content_type',
     'mkdir',
+    'mktime',
     'msg_get_queue',
     'msg_queue_exists',
     'msg_receive',
diff --git a/generated/8.5/rector-migrate.php b/generated/8.5/rector-migrate.php
index 20a1400d..bf706d06 100644
--- a/generated/8.5/rector-migrate.php
+++ b/generated/8.5/rector-migrate.php
@@ -251,6 +251,7 @@
             'get_include_path' => 'Safe\get_include_path',
             'get_meta_tags' => 'Safe\get_meta_tags',
             'glob' => 'Safe\glob',
+            'gmmktime' => 'Safe\gmmktime',
             'gmstrftime' => 'Safe\gmstrftime',
             'gnupg_adddecryptkey' => 'Safe\gnupg_adddecryptkey',
             'gnupg_addencryptkey' => 'Safe\gnupg_addencryptkey',
@@ -514,6 +515,7 @@
             'md5_file' => 'Safe\md5_file',
             'mime_content_type' => 'Safe\mime_content_type',
             'mkdir' => 'Safe\mkdir',
+            'mktime' => 'Safe\mktime',
             'msg_get_queue' => 'Safe\msg_get_queue',
             'msg_queue_exists' => 'Safe\msg_queue_exists',
             'msg_receive' => 'Safe\msg_receive',
diff --git a/generator/config/detectErrorType.php b/generator/config/detectErrorType.php
index 74ca5ca3..4749960b 100644
--- a/generator/config/detectErrorType.php
+++ b/generator/config/detectErrorType.php
@@ -53,6 +53,7 @@
         "/If an error occurs, returns &false;./m", // ftell, popen
         '/On failure to change the value, &false; is returned./m', // session_cache_expire, session_cache_limiter
         '/This function returns &true; if a session was successfully started,\s+otherwise &false;./m', // session_start
+        '/&false;\s+if\s+the\s+timestamp\s+doesn\'t\s+fit\s+in\s+a\s+PHP\s+integer./m', // gmmktime / mktime
     ];
     foreach ($falsies as $falsie) {
         if (preg_match($falsie, $text)) {