diff --git a/admin/admin_user_search.php b/admin/admin_user_search.php
index f0f5a956d..6bd5a9140 100644
--- a/admin/admin_user_search.php
+++ b/admin/admin_user_search.php
@@ -255,7 +255,7 @@ if (!isset($_REQUEST['dosearch'])) {
 
             $username = str_replace("\*", '%', trim(strip_tags(strtolower($username))));
 
-            if (false !== strpos($username, '%')) {
+            if (str_contains($username, '%')) {
                 $op = 'LIKE';
             } else {
                 $op = '=';
@@ -276,7 +276,7 @@ if (!isset($_REQUEST['dosearch'])) {
 
             $email = str_replace("\*", '%', trim(strip_tags(strtolower($email))));
 
-            if (false !== strpos($email, '%')) {
+            if (str_contains($email, '%')) {
                 $op = 'LIKE';
             } else {
                 $op = '=';
@@ -524,7 +524,7 @@ if (!isset($_REQUEST['dosearch'])) {
                     break;
                 case 'equals':
                     // looking for a -
-                    if (false !== strpos($postcount_value, '-')) {
+                    if (str_contains($postcount_value, '-')) {
                         $range = preg_split('/[-\s]+/', $postcount_value);
 
                         $range_begin = (int)$range[0];
@@ -571,7 +571,7 @@ if (!isset($_REQUEST['dosearch'])) {
 
             $userfield_value = str_replace("\*", '%', trim(strip_tags(strtolower($userfield_value))));
 
-            if (false !== strpos($userfield_value, '%')) {
+            if (str_contains($userfield_value, '%')) {
                 $op = 'LIKE';
             } else {
                 $op = '=';
diff --git a/bt/announce.php b/bt/announce.php
index 79dec7adb..2a2a42fb0 100644
--- a/bt/announce.php
+++ b/bt/announce.php
@@ -27,7 +27,7 @@ if (isset($_GET['?info_hash']) && !isset($_GET['info_hash'])) {
 }
 
 // Initial request verification
-if (strpos($_SERVER['REQUEST_URI'], 'scrape') !== false) {
+if (str_contains($_SERVER['REQUEST_URI'], 'scrape')) {
     msg_die('Please disable SCRAPE!');
 }
 
diff --git a/dl.php b/dl.php
index d74d3943d..d3f6f4a8a 100644
--- a/dl.php
+++ b/dl.php
@@ -38,7 +38,7 @@ function send_file_to_browser($attachment, $upload_dir)
 
     // Correct the mime type - we force application/octet-stream for all files, except images
     // Please do not change this, it is a security precaution
-    if (false === strpos($attachment['mimetype'], 'image')) {
+    if (!str_contains($attachment['mimetype'], 'image')) {
         $attachment['mimetype'] = 'application/octet-stream';
     }
 
diff --git a/library/ajax/manage_admin.php b/library/ajax/manage_admin.php
index 869eebcd6..9a4019b51 100644
--- a/library/ajax/manage_admin.php
+++ b/library/ajax/manage_admin.php
@@ -41,7 +41,7 @@ switch ($mode) {
         $dir = $template->cachedir;
         $res = @opendir($dir);
         while (($file = readdir($res)) !== false) {
-            if (0 === strpos($file, $match)) {
+            if (str_starts_with($file, $match)) {
                 @unlink($dir . $file);
             }
         }
diff --git a/library/attach_mod/includes/functions_attach.php b/library/attach_mod/includes/functions_attach.php
index 5c0b7f22c..46433e857 100644
--- a/library/attach_mod/includes/functions_attach.php
+++ b/library/attach_mod/includes/functions_attach.php
@@ -382,7 +382,7 @@ function attachment_sync_topic($topics)
  */
 function get_extension($filename)
 {
-    if (false === strpos($filename, '.')) {
+    if (!str_contains($filename, '.')) {
         return '';
     }
     $extension = strrchr(strtolower($filename), '.');
diff --git a/library/attach_mod/includes/functions_delete.php b/library/attach_mod/includes/functions_delete.php
index b462226c6..adc1672f9 100644
--- a/library/attach_mod/includes/functions_delete.php
+++ b/library/attach_mod/includes/functions_delete.php
@@ -26,9 +26,9 @@ function delete_attachment($post_id_array = 0, $attach_id_array = 0, $page = 0,
         $post_id_array = [];
 
         if (!is_array($attach_id_array)) {
-            if (false !== strpos($attach_id_array, ', ')) {
+            if (str_contains($attach_id_array, ', ')) {
                 $attach_id_array = explode(', ', $attach_id_array);
-            } elseif (false !== strpos($attach_id_array, ',')) {
+            } elseif (str_contains($attach_id_array, ',')) {
                 $attach_id_array = explode(',', $attach_id_array);
             } else {
                 $attach_id = (int)$attach_id_array;
@@ -67,9 +67,9 @@ function delete_attachment($post_id_array = 0, $attach_id_array = 0, $page = 0,
             return;
         }
 
-        if (false !== strpos($post_id_array, ', ')) {
+        if (str_contains($post_id_array, ', ')) {
             $post_id_array = explode(', ', $post_id_array);
-        } elseif (false !== strpos($post_id_array, ',')) {
+        } elseif (str_contains($post_id_array, ',')) {
             $post_id_array = explode(',', $post_id_array);
         } else {
             $post_id = (int)$post_id_array;
@@ -112,9 +112,9 @@ function delete_attachment($post_id_array = 0, $attach_id_array = 0, $page = 0,
     }
 
     if (!is_array($attach_id_array)) {
-        if (false !== strpos($attach_id_array, ', ')) {
+        if (str_contains($attach_id_array, ', ')) {
             $attach_id_array = explode(', ', $attach_id_array);
-        } elseif (false !== strpos($attach_id_array, ',')) {
+        } elseif (str_contains($attach_id_array, ',')) {
             $attach_id_array = explode(',', $attach_id_array);
         } else {
             $attach_id = (int)$attach_id_array;
diff --git a/library/defines.php b/library/defines.php
index 4646deb2e..a54af9007 100644
--- a/library/defines.php
+++ b/library/defines.php
@@ -97,7 +97,7 @@ define('CRON_RUNNING', TRIGGERS_DIR . '/cron_running');
 
 // Gzip
 define('GZIP_OUTPUT_ALLOWED', extension_loaded('zlib') && !ini_get('zlib.output_compression'));
-define('UA_GZIP_SUPPORTED', isset($_SERVER['HTTP_ACCEPT_ENCODING']) && strpos($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip') !== false);
+define('UA_GZIP_SUPPORTED', isset($_SERVER['HTTP_ACCEPT_ENCODING']) && str_contains($_SERVER['HTTP_ACCEPT_ENCODING'], 'gzip'));
 
 // Torrents (reserved: -1)
 define('TOR_NOT_APPROVED', 0); // не проверено
diff --git a/library/includes/functions.php b/library/includes/functions.php
index 8dd9206d2..e1b39b9ff 100644
--- a/library/includes/functions.php
+++ b/library/includes/functions.php
@@ -553,7 +553,7 @@ function url_arg($url, $arg, $value, $amp = '&')
         $url = str_replace($cur, $new, $url);
     } // добавляем параметр
     elseif (null !== $value) {
-        $div = (strpos($url, '?') !== false) ? $amp : '?';
+        $div = str_contains($url, '?') ? $amp : '?';
         $url = $url . $div . $arg . '=' . urlencode($value);
     }
     return $url . $anchor;
@@ -1469,7 +1469,7 @@ function redirect($url)
         trigger_error("Headers already sent in $filename($linenum)", E_USER_ERROR);
     }
 
-    if (false !== strpos(urldecode($url), "\n") || false !== strpos(urldecode($url), "\r") || false !== strpos(urldecode($url), ';url')) {
+    if (str_contains(urldecode($url), "\n") || str_contains(urldecode($url), "\r") || str_contains(urldecode($url), ';url')) {
         bb_die('Tried to redirect to potentially insecure url');
     }
 
diff --git a/login.php b/login.php
index 5dc20198e..5cfd5627b 100644
--- a/login.php
+++ b/login.php
@@ -32,7 +32,7 @@ $login_errors = [];
 if (preg_match('/^redirect=([a-z0-9\.#\/\?&=\+\-_]+)/si', $_SERVER['QUERY_STRING'], $matches)) {
     $redirect_url = $matches[1];
 
-    if (false === strpos($redirect_url, '?') && $first_amp = strpos($redirect_url, '&')) {
+    if (!str_contains($redirect_url, '?') && $first_amp = strpos($redirect_url, '&')) {
         $redirect_url[$first_amp] = '?';
     }
 } elseif (!empty($_POST['redirect'])) {
@@ -43,7 +43,7 @@ if (preg_match('/^redirect=([a-z0-9\.#\/\?&=\+\-_]+)/si', $_SERVER['QUERY_STRING
 
 $redirect_url = str_replace(['&admin=1', '?admin=1'], '', $redirect_url);
 
-if (!$redirect_url || false !== strpos(urldecode($redirect_url), "\n") || false !== strpos(urldecode($redirect_url), "\r") || false !== strpos(urldecode($redirect_url), ';url')) {
+if (!$redirect_url || str_contains(urldecode($redirect_url), "\n") || str_contains(urldecode($redirect_url), "\r") || str_contains(urldecode($redirect_url), ';url')) {
     $redirect_url = 'index.php';
 }
 
diff --git a/src/Helpers/IPHelper.php b/src/Helpers/IPHelper.php
index 664e58d03..cfa1dfe81 100644
--- a/src/Helpers/IPHelper.php
+++ b/src/Helpers/IPHelper.php
@@ -29,7 +29,7 @@ class IPHelper extends Ip
     public static function anonymizeIP(string $ip): string
     {
         $wrappedIPv6 = false;
-        if ('[' === substr($ip, 0, 1) && ']' === substr($ip, -1, 1)) {
+        if (str_starts_with($ip, '[') && str_ends_with($ip, ']')) {
             $wrappedIPv6 = true;
             $ip = substr($ip, 1, -1);
         }
diff --git a/src/Legacy/BBCode.php b/src/Legacy/BBCode.php
index 3ffb4fcbc..7684e7b88 100644
--- a/src/Legacy/BBCode.php
+++ b/src/Legacy/BBCode.php
@@ -169,7 +169,7 @@ class BBCode
     private function parse($text): string
     {
         // Tag parse
-        if (strpos($text, '[') === false) {
+        if (!str_contains($text, '[')) {
             return $text;
         }
 
diff --git a/src/Legacy/SqlDb.php b/src/Legacy/SqlDb.php
index 345c23cea..f6a772759 100644
--- a/src/Legacy/SqlDb.php
+++ b/src/Legacy/SqlDb.php
@@ -968,7 +968,7 @@ class SqlDb
                     $query = "SELECT * FROM $m[1] WHERE $m[2]";
                 }
 
-                if (0 === strpos($query, "SELECT")) {
+                if (str_starts_with($query, "SELECT")) {
                     $html_table = false;
 
                     if ($result = mysqli_query($this->link, "EXPLAIN $query")) {
diff --git a/src/Legacy/Template.php b/src/Legacy/Template.php
index ca028202e..b05826bb4 100644
--- a/src/Legacy/Template.php
+++ b/src/Legacy/Template.php
@@ -310,7 +310,7 @@ class Template
      */
     public function assign_block_vars($blockname, $vararray)
     {
-        if (false !== strpos($blockname, '.')) {
+        if (str_contains($blockname, '.')) {
             // Nested block.
             $blocks = explode('.', $blockname);
             $blockcount = \count($blocks) - 1;
@@ -994,7 +994,7 @@ class Template
         $this->vars['LANG'] ??= $bb_cfg['default_lang'];
         // adding current template
         $tpl = $this->root . '/';
-        if (0 === strpos($tpl, './')) {
+        if (str_starts_with($tpl, './')) {
             $tpl = substr($tpl, 2, \strlen($tpl));
         }
         $this->vars['TEMPLATE'] ??= $tpl;