diff --git a/.php-cs-fixer.dist.php b/.php-cs-fixer.dist.php
index c9c24c7a06f8..e9240c590917 100644
--- a/.php-cs-fixer.dist.php
+++ b/.php-cs-fixer.dist.php
@@ -40,17 +40,7 @@
     ]);
 
 $overrides = [
-    'get_class_to_class_keyword'  => true,
-    'trailing_comma_in_multiline' => [
-        'after_heredoc' => true,
-        'elements'      => [
-            'arguments',
-            'array_destructuring',
-            'arrays',
-            'match',
-            'parameters',
-        ],
-    ],
+    'modernize_strpos' => ['modernize_stripos' => true],
 ];
 
 $options = [
diff --git a/system/Database/Forge.php b/system/Database/Forge.php
index 83cf1b88d9f4..6bf574818919 100644
--- a/system/Database/Forge.php
+++ b/system/Database/Forge.php
@@ -1061,7 +1061,7 @@ protected function _attributeUnique(array &$attributes, array &$field)
     protected function _attributeAutoIncrement(array &$attributes, array &$field)
     {
         if (! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === true
-            && stripos($field['type'], 'int') !== false
+            && str_contains(strtolower($field['type']), 'int')
         ) {
             $field['auto_increment'] = ' AUTO_INCREMENT';
         }
diff --git a/system/Database/OCI8/Forge.php b/system/Database/OCI8/Forge.php
index 4b09372d778e..f761045d9784 100644
--- a/system/Database/OCI8/Forge.php
+++ b/system/Database/OCI8/Forge.php
@@ -184,7 +184,7 @@ protected function _alterTable(string $alterType, string $table, $processedField
     protected function _attributeAutoIncrement(array &$attributes, array &$field)
     {
         if (! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === true
-            && stripos($field['type'], 'NUMBER') !== false
+            && str_contains(strtolower($field['type']), 'number')
             && version_compare($this->db->getVersion(), '12.1', '>=')
         ) {
             $field['auto_increment'] = ' GENERATED BY DEFAULT ON NULL AS IDENTITY';
diff --git a/system/Database/Postgre/Forge.php b/system/Database/Postgre/Forge.php
index 704f3e576047..b0a38c90ed23 100644
--- a/system/Database/Postgre/Forge.php
+++ b/system/Database/Postgre/Forge.php
@@ -154,7 +154,7 @@ protected function _processColumn(array $processedField): string
     protected function _attributeType(array &$attributes)
     {
         // Reset field lengths for data types that don't support it
-        if (isset($attributes['CONSTRAINT']) && stripos($attributes['TYPE'], 'int') !== false) {
+        if (isset($attributes['CONSTRAINT']) && str_contains(strtolower($attributes['TYPE']), 'int')) {
             $attributes['CONSTRAINT'] = null;
         }
 
diff --git a/system/Database/SQLSRV/Forge.php b/system/Database/SQLSRV/Forge.php
index f187b9981f88..7b1da6e85ba7 100644
--- a/system/Database/SQLSRV/Forge.php
+++ b/system/Database/SQLSRV/Forge.php
@@ -360,7 +360,7 @@ protected function _processColumn(array $processedField): string
     protected function _attributeType(array &$attributes)
     {
         // Reset field lengths for data types that don't support it
-        if (isset($attributes['CONSTRAINT']) && stripos($attributes['TYPE'], 'int') !== false) {
+        if (isset($attributes['CONSTRAINT']) && str_contains(strtolower($attributes['TYPE']), 'int')) {
             $attributes['CONSTRAINT'] = null;
         }
 
@@ -412,7 +412,7 @@ protected function _attributeType(array &$attributes)
      */
     protected function _attributeAutoIncrement(array &$attributes, array &$field)
     {
-        if (! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === true && stripos($field['type'], 'INT') !== false) {
+        if (! empty($attributes['AUTO_INCREMENT']) && $attributes['AUTO_INCREMENT'] === true && str_contains(strtolower($field['type']), strtolower('INT'))) {
             $field['auto_increment'] = ' IDENTITY(1,1)';
         }
     }
diff --git a/system/Database/SQLite3/Forge.php b/system/Database/SQLite3/Forge.php
index 03120dd7a0da..31c2a7ed58a6 100644
--- a/system/Database/SQLite3/Forge.php
+++ b/system/Database/SQLite3/Forge.php
@@ -226,7 +226,7 @@ protected function _attributeAutoIncrement(array &$attributes, array &$field)
         if (
             ! empty($attributes['AUTO_INCREMENT'])
             && $attributes['AUTO_INCREMENT'] === true
-            && stripos($field['type'], 'int') !== false
+            && str_contains(strtolower($field['type']), 'int')
         ) {
             $field['type']           = 'INTEGER PRIMARY KEY';
             $field['default']        = '';
diff --git a/system/Helpers/form_helper.php b/system/Helpers/form_helper.php
index ae4505c26597..7b89bb9ec173 100644
--- a/system/Helpers/form_helper.php
+++ b/system/Helpers/form_helper.php
@@ -49,10 +49,10 @@ function form_open(string $action = '', $attributes = [], array $hidden = []): s
 
         $attributes = stringify_attributes($attributes);
 
-        if (stripos($attributes, 'method=') === false) {
+        if (! str_contains(strtolower($attributes), 'method=')) {
             $attributes .= ' method="post"';
         }
-        if (stripos($attributes, 'accept-charset=') === false) {
+        if (! str_contains(strtolower($attributes), 'accept-charset=')) {
             $config = config(App::class);
             $attributes .= ' accept-charset="' . strtolower($config->charset) . '"';
         }
@@ -62,7 +62,7 @@ function form_open(string $action = '', $attributes = [], array $hidden = []): s
         // Add CSRF field if enabled, but leave it out for GET requests and requests to external websites
         $before = service('filters')->getFilters()['before'];
 
-        if ((in_array('csrf', $before, true) || array_key_exists('csrf', $before)) && str_contains($action, base_url()) && stripos($form, 'method="get"') === false) {
+        if ((in_array('csrf', $before, true) || array_key_exists('csrf', $before)) && str_contains($action, base_url()) && ! str_contains(strtolower($form), strtolower('method="get"'))) {
             $form .= csrf_field($csrfId ?? null);
         }
 
@@ -223,11 +223,11 @@ function form_textarea($data = '', string $value = '', $extra = ''): string
         }
 
         // Unsets default rows and cols if defined in extra field as array or string.
-        if ((is_array($extra) && array_key_exists('rows', $extra)) || (is_string($extra) && stripos(preg_replace('/\s+/', '', $extra), 'rows=') !== false)) {
+        if ((is_array($extra) && array_key_exists('rows', $extra)) || (is_string($extra) && str_contains(strtolower(preg_replace('/\s+/', '', $extra)), 'rows='))) {
             unset($defaults['rows']);
         }
 
-        if ((is_array($extra) && array_key_exists('cols', $extra)) || (is_string($extra) && stripos(preg_replace('/\s+/', '', $extra), 'cols=') !== false)) {
+        if ((is_array($extra) && array_key_exists('cols', $extra)) || (is_string($extra) && str_contains(strtolower(preg_replace('/\s+/', '', $extra)), 'cols='))) {
             unset($defaults['cols']);
         }
 
@@ -248,7 +248,7 @@ function form_multiselect($name = '', array $options = [], array $selected = [],
     {
         $extra = stringify_attributes($extra);
 
-        if (stripos($extra, 'multiple') === false) {
+        if (! str_contains(strtolower($extra), strtolower('multiple'))) {
             $extra .= ' multiple="multiple"';
         }
 
@@ -305,7 +305,7 @@ function form_dropdown($data = '', $options = [], $selected = [], $extra = ''):
         }
 
         $extra    = stringify_attributes($extra);
-        $multiple = (count($selected) > 1 && stripos($extra, 'multiple') === false) ? ' multiple="multiple"' : '';
+        $multiple = (count($selected) > 1 && ! str_contains(strtolower($extra), 'multiple')) ? ' multiple="multiple"' : '';
         $form     = '<select ' . rtrim(parse_form_attributes($data, $defaults)) . $extra . $multiple . ">\n";
 
         foreach ($options as $key => $val) {
diff --git a/system/Test/CIUnitTestCase.php b/system/Test/CIUnitTestCase.php
index 2797e63d8193..997c0cded837 100644
--- a/system/Test/CIUnitTestCase.php
+++ b/system/Test/CIUnitTestCase.php
@@ -516,7 +516,7 @@ protected function getHeaderEmitted(string $header, bool $ignoreCase = false, st
 
         foreach (xdebug_get_headers() as $emittedHeader) {
             $found = $ignoreCase
-                ? (stripos($emittedHeader, $header) === 0)
+                ? (str_starts_with(strtolower($emittedHeader), strtolower($header)))
                 : (str_starts_with($emittedHeader, $header));
 
             if ($found) {
diff --git a/system/Test/Fabricator.php b/system/Test/Fabricator.php
index f80ea201b9e9..ffd4cd288450 100644
--- a/system/Test/Fabricator.php
+++ b/system/Test/Fabricator.php
@@ -379,12 +379,12 @@ protected function guessFormatter($field): string
 
         // Check some common partials
         foreach (['email', 'name', 'title', 'text', 'date', 'url'] as $term) {
-            if (stripos($field, $term) !== false) {
+            if (str_contains(strtolower($field), strtolower($term))) {
                 return $term;
             }
         }
 
-        if (stripos($field, 'phone') !== false) {
+        if (str_contains(strtolower($field), 'phone')) {
             return 'phoneNumber';
         }
 
diff --git a/tests/system/Cache/CacheFactoryTest.php b/tests/system/Cache/CacheFactoryTest.php
index 0947f31d5045..d8d301efa4a7 100644
--- a/tests/system/Cache/CacheFactoryTest.php
+++ b/tests/system/Cache/CacheFactoryTest.php
@@ -96,7 +96,7 @@ public function testHandlesBadHandler(): void
 
         $this->config->handler = 'dummy';
 
-        if (stripos('win', php_uname()) === 0) {
+        if (str_starts_with('win', strtolower(php_uname()))) {
             $this->assertTrue(true); // can't test properly if we are on Windows
         } else {
             $this->assertInstanceOf(DummyHandler::class, $this->cacheFactory->getHandler($this->config, 'wincache', 'wincache'));