diff --git a/.php_cs.dist b/.php_cs.dist
index ff8a55dbb..1b31c0a3d 100644
--- a/.php_cs.dist
+++ b/.php_cs.dist
@@ -11,6 +11,7 @@ return PhpCsFixer\Config::create()
         'heredoc_to_nowdoc' => false,
         'ordered_imports' => true,
         'phpdoc_types_order' => ['null_adjustment' => 'always_last', 'sort_algorithm' => 'none'],
+        'native_function_invocation' => ['include' => ['@compiler_optimized'], 'scope' => 'all'],
     ])
     ->setRiskyAllowed(true)
     ->setFinder(PhpCsFixer\Finder::create()->in(__DIR__))
diff --git a/lib/Twig/Cache/Filesystem.php b/lib/Twig/Cache/Filesystem.php
index b2704dd6b..73b0220eb 100644
--- a/lib/Twig/Cache/Filesystem.php
+++ b/lib/Twig/Cache/Filesystem.php
@@ -47,7 +47,7 @@ class Twig_Cache_Filesystem implements Twig_CacheInterface
 
     public function write($key, $content)
     {
-        $dir = dirname($key);
+        $dir = \dirname($key);
         if (!is_dir($dir)) {
             if (false === @mkdir($dir, 0777, true)) {
                 clearstatcache(true, $dir);
@@ -65,9 +65,9 @@ class Twig_Cache_Filesystem implements Twig_CacheInterface
 
             if (self::FORCE_BYTECODE_INVALIDATION == ($this->options & self::FORCE_BYTECODE_INVALIDATION)) {
                 // Compile cached file into bytecode cache
-                if (function_exists('opcache_invalidate')) {
+                if (\function_exists('opcache_invalidate')) {
                     opcache_invalidate($key, true);
-                } elseif (function_exists('apc_compile_file')) {
+                } elseif (\function_exists('apc_compile_file')) {
                     apc_compile_file($key);
                 }
             }
diff --git a/lib/Twig/Error/Syntax.php b/lib/Twig/Error/Syntax.php
index c59b03577..dca85d62f 100644
--- a/lib/Twig/Error/Syntax.php
+++ b/lib/Twig/Error/Syntax.php
@@ -28,7 +28,7 @@ class Twig_Error_Syntax extends Twig_Error
         $alternatives = [];
         foreach ($items as $item) {
             $lev = levenshtein($name, $item);
-            if ($lev <= strlen($name) / 3 || false !== strpos($item, $name)) {
+            if ($lev <= \strlen($name) / 3 || false !== strpos($item, $name)) {
                 $alternatives[$item] = $lev;
             }
         }
diff --git a/lib/Twig/Extension/Escaper.php b/lib/Twig/Extension/Escaper.php
index d4808f6d8..304753caa 100644
--- a/lib/Twig/Extension/Escaper.php
+++ b/lib/Twig/Extension/Escaper.php
@@ -68,8 +68,8 @@ final class Twig_Extension_Escaper extends Twig_Extension
     {
         // disable string callables to avoid calling a function named html or js,
         // or any other upcoming escaping strategy
-        if (!is_string($this->defaultStrategy) && false !== $this->defaultStrategy) {
-            return call_user_func($this->defaultStrategy, $name);
+        if (!\is_string($this->defaultStrategy) && false !== $this->defaultStrategy) {
+            return \call_user_func($this->defaultStrategy, $name);
         }
 
         return $this->defaultStrategy;
diff --git a/lib/Twig/Extension/Profiler.php b/lib/Twig/Extension/Profiler.php
index 065b221e8..1ed7fe288 100644
--- a/lib/Twig/Extension/Profiler.php
+++ b/lib/Twig/Extension/Profiler.php
@@ -29,14 +29,14 @@ class Twig_Extension_Profiler extends Twig_Extension
         $profile->leave();
         array_shift($this->actives);
 
-        if (1 === count($this->actives)) {
+        if (1 === \count($this->actives)) {
             $this->actives[0]->leave();
         }
     }
 
     public function getNodeVisitors()
     {
-        return [new Twig_Profiler_NodeVisitor_Profiler(get_class($this))];
+        return [new Twig_Profiler_NodeVisitor_Profiler(\get_class($this))];
     }
 }
 
diff --git a/lib/Twig/Extension/Sandbox.php b/lib/Twig/Extension/Sandbox.php
index 77b23c57d..e59c77e1e 100644
--- a/lib/Twig/Extension/Sandbox.php
+++ b/lib/Twig/Extension/Sandbox.php
@@ -84,7 +84,7 @@ final class Twig_Extension_Sandbox extends Twig_Extension
 
     public function ensureToStringAllowed($obj)
     {
-        if ($this->isSandboxed() && is_object($obj)) {
+        if ($this->isSandboxed() && \is_object($obj)) {
             $this->policy->checkMethodAllowed($obj, '__toString');
         }
 
diff --git a/lib/Twig/FileExtensionEscapingStrategy.php b/lib/Twig/FileExtensionEscapingStrategy.php
index 6b13c7213..7854f7691 100644
--- a/lib/Twig/FileExtensionEscapingStrategy.php
+++ b/lib/Twig/FileExtensionEscapingStrategy.php
@@ -31,7 +31,7 @@ class Twig_FileExtensionEscapingStrategy
      */
     public static function guess($name)
     {
-        if (in_array(substr($name, -1), ['/', '\\'])) {
+        if (\in_array(substr($name, -1), ['/', '\\'])) {
             return 'html'; // return html for directories
         }
 
diff --git a/lib/Twig/Node/Expression/Filter/Default.php b/lib/Twig/Node/Expression/Filter/Default.php
index 2aeb742d7..9bac0e162 100644
--- a/lib/Twig/Node/Expression/Filter/Default.php
+++ b/lib/Twig/Node/Expression/Filter/Default.php
@@ -24,7 +24,7 @@ class Twig_Node_Expression_Filter_Default extends Twig_Node_Expression_Filter
 
         if ('default' === $filterName->getAttribute('value') && ($node instanceof Twig_Node_Expression_Name || $node instanceof Twig_Node_Expression_GetAttr)) {
             $test = new Twig_Node_Expression_Test_Defined(clone $node, 'defined', new Twig_Node(), $node->getTemplateLine());
-            $false = count($arguments) ? $arguments->getNode(0) : new Twig_Node_Expression_Constant('', $node->getTemplateLine());
+            $false = \count($arguments) ? $arguments->getNode(0) : new Twig_Node_Expression_Constant('', $node->getTemplateLine());
 
             $node = new Twig_Node_Expression_Conditional($test, $default, $false, $node->getTemplateLine());
         } else {
diff --git a/lib/Twig/Node/If.php b/lib/Twig/Node/If.php
index 2980a673c..094720ad3 100644
--- a/lib/Twig/Node/If.php
+++ b/lib/Twig/Node/If.php
@@ -30,7 +30,7 @@ class Twig_Node_If extends Twig_Node
     public function compile(Twig_Compiler $compiler)
     {
         $compiler->addDebugInfo($this);
-        for ($i = 0, $count = count($this->getNode('tests')); $i < $count; $i += 2) {
+        for ($i = 0, $count = \count($this->getNode('tests')); $i < $count; $i += 2) {
             if ($i > 0) {
                 $compiler
                     ->outdent()
diff --git a/lib/Twig/Node/Macro.php b/lib/Twig/Node/Macro.php
index 1f0d46823..33a9e57b7 100644
--- a/lib/Twig/Node/Macro.php
+++ b/lib/Twig/Node/Macro.php
@@ -36,7 +36,7 @@ class Twig_Node_Macro extends Twig_Node
             ->write(sprintf('public function macro_%s(', $this->getAttribute('name')))
         ;
 
-        $count = count($this->getNode('arguments'));
+        $count = \count($this->getNode('arguments'));
         $pos = 0;
         foreach ($this->getNode('arguments') as $name => $default) {
             $compiler
diff --git a/lib/Twig/Node/Set.php b/lib/Twig/Node/Set.php
index 0db73093a..815bbe41d 100644
--- a/lib/Twig/Node/Set.php
+++ b/lib/Twig/Node/Set.php
@@ -40,7 +40,7 @@ class Twig_Node_Set extends Twig_Node implements Twig_NodeCaptureInterface
     {
         $compiler->addDebugInfo($this);
 
-        if (count($this->getNode('names')) > 1) {
+        if (\count($this->getNode('names')) > 1) {
             $compiler->write('list(');
             foreach ($this->getNode('names') as $idx => $node) {
                 if ($idx) {
@@ -68,7 +68,7 @@ class Twig_Node_Set extends Twig_Node implements Twig_NodeCaptureInterface
         if (!$this->getAttribute('capture')) {
             $compiler->raw(' = ');
 
-            if (count($this->getNode('names')) > 1) {
+            if (\count($this->getNode('names')) > 1) {
                 $compiler->write('[');
                 foreach ($this->getNode('values') as $idx => $value) {
                     if ($idx) {
diff --git a/lib/Twig/NodeVisitor/Escaper.php b/lib/Twig/NodeVisitor/Escaper.php
index 628a1954c..d9228d70c 100644
--- a/lib/Twig/NodeVisitor/Escaper.php
+++ b/lib/Twig/NodeVisitor/Escaper.php
@@ -80,7 +80,7 @@ final class Twig_NodeVisitor_Escaper extends Twig_BaseNodeVisitor
             return $node;
         }
 
-        $class = get_class($node);
+        $class = \get_class($node);
 
         return new $class(
             $this->getEscaperFilter($type, $expression),
@@ -122,13 +122,13 @@ final class Twig_NodeVisitor_Escaper extends Twig_BaseNodeVisitor
             $safe = $this->safeAnalysis->getSafe($expression);
         }
 
-        return in_array($type, $safe) || in_array('all', $safe);
+        return \in_array($type, $safe) || \in_array('all', $safe);
     }
 
     private function needEscaping(Twig_Environment $env)
     {
-        if (count($this->statusStack)) {
-            return $this->statusStack[count($this->statusStack) - 1];
+        if (\count($this->statusStack)) {
+            return $this->statusStack[\count($this->statusStack) - 1];
         }
 
         return $this->defaultStrategy ? $this->defaultStrategy : false;
diff --git a/lib/Twig/Profiler/Dumper/Base.php b/lib/Twig/Profiler/Dumper/Base.php
index 913afd4f0..8aeeeb773 100644
--- a/lib/Twig/Profiler/Dumper/Base.php
+++ b/lib/Twig/Profiler/Dumper/Base.php
@@ -49,7 +49,7 @@ abstract class Twig_Profiler_Dumper_Base
             $str = sprintf("%s %s\n", $start, $this->formatTime($profile, $percent));
         }
 
-        $nCount = count($profile->getProfiles());
+        $nCount = \count($profile->getProfiles());
         foreach ($profile as $i => $p) {
             $str .= $this->dumpProfile($p, $prefix, $i + 1 !== $nCount);
         }
diff --git a/lib/Twig/Sandbox/SecurityPolicy.php b/lib/Twig/Sandbox/SecurityPolicy.php
index 9c0d35229..b9433c0b7 100644
--- a/lib/Twig/Sandbox/SecurityPolicy.php
+++ b/lib/Twig/Sandbox/SecurityPolicy.php
@@ -45,7 +45,7 @@ final class Twig_Sandbox_SecurityPolicy implements Twig_Sandbox_SecurityPolicyIn
     {
         $this->allowedMethods = [];
         foreach ($methods as $class => $m) {
-            $this->allowedMethods[$class] = array_map('strtolower', is_array($m) ? $m : [$m]);
+            $this->allowedMethods[$class] = array_map('strtolower', \is_array($m) ? $m : [$m]);
         }
     }
 
@@ -62,19 +62,19 @@ final class Twig_Sandbox_SecurityPolicy implements Twig_Sandbox_SecurityPolicyIn
     public function checkSecurity($tags, $filters, $functions)
     {
         foreach ($tags as $tag) {
-            if (!in_array($tag, $this->allowedTags)) {
+            if (!\in_array($tag, $this->allowedTags)) {
                 throw new Twig_Sandbox_SecurityNotAllowedTagError(sprintf('Tag "%s" is not allowed.', $tag), $tag);
             }
         }
 
         foreach ($filters as $filter) {
-            if (!in_array($filter, $this->allowedFilters)) {
+            if (!\in_array($filter, $this->allowedFilters)) {
                 throw new Twig_Sandbox_SecurityNotAllowedFilterError(sprintf('Filter "%s" is not allowed.', $filter), $filter);
             }
         }
 
         foreach ($functions as $function) {
-            if (!in_array($function, $this->allowedFunctions)) {
+            if (!\in_array($function, $this->allowedFunctions)) {
                 throw new Twig_Sandbox_SecurityNotAllowedFunctionError(sprintf('Function "%s" is not allowed.', $function), $function);
             }
         }
@@ -90,14 +90,14 @@ final class Twig_Sandbox_SecurityPolicy implements Twig_Sandbox_SecurityPolicyIn
         $method = strtolower($method);
         foreach ($this->allowedMethods as $class => $methods) {
             if ($obj instanceof $class) {
-                $allowed = in_array($method, $methods);
+                $allowed = \in_array($method, $methods);
 
                 break;
             }
         }
 
         if (!$allowed) {
-            $class = get_class($obj);
+            $class = \get_class($obj);
             throw new Twig_Sandbox_SecurityNotAllowedMethodError(sprintf('Calling "%s" method on a "%s" object is not allowed.', $method, $class), $class, $method);
         }
     }
@@ -107,14 +107,14 @@ final class Twig_Sandbox_SecurityPolicy implements Twig_Sandbox_SecurityPolicyIn
         $allowed = false;
         foreach ($this->allowedProperties as $class => $properties) {
             if ($obj instanceof $class) {
-                $allowed = in_array($property, is_array($properties) ? $properties : [$properties]);
+                $allowed = \in_array($property, \is_array($properties) ? $properties : [$properties]);
 
                 break;
             }
         }
 
         if (!$allowed) {
-            $class = get_class($obj);
+            $class = \get_class($obj);
             throw new Twig_Sandbox_SecurityNotAllowedPropertyError(sprintf('Calling "%s" property on a "%s" object is not allowed.', $property, $class), $class, $property);
         }
     }
diff --git a/lib/Twig/Token.php b/lib/Twig/Token.php
index c054c7e77..4244e857d 100644
--- a/lib/Twig/Token.php
+++ b/lib/Twig/Token.php
@@ -67,14 +67,14 @@ final class Twig_Token
      */
     public function test($type, $values = null)
     {
-        if (null === $values && !is_int($type)) {
+        if (null === $values && !\is_int($type)) {
             $values = $type;
             $type = self::NAME_TYPE;
         }
 
         return ($this->type === $type) && (
             null === $values ||
-            (is_array($values) && in_array($this->value, $values)) ||
+            (\is_array($values) && \in_array($this->value, $values)) ||
             $this->value == $values
         );
     }
diff --git a/lib/Twig/TokenParser/For.php b/lib/Twig/TokenParser/For.php
index b41340579..0177a2889 100644
--- a/lib/Twig/TokenParser/For.php
+++ b/lib/Twig/TokenParser/For.php
@@ -44,7 +44,7 @@ final class Twig_TokenParser_For extends Twig_TokenParser
         }
         $stream->expect(/* Twig_Token::BLOCK_END_TYPE */ 3);
 
-        if (count($targets) > 1) {
+        if (\count($targets) > 1) {
             $keyTarget = $targets->getNode(0);
             $keyTarget = new Twig_Node_Expression_AssignName($keyTarget->getAttribute('name'), $keyTarget->getTemplateLine());
             $valueTarget = $targets->getNode(1);
@@ -95,7 +95,7 @@ final class Twig_TokenParser_For extends Twig_TokenParser
     {
         if ($node instanceof Twig_Node_Expression_GetAttr && $node->getNode('node') instanceof Twig_Node_Expression_Name && 'loop' == $node->getNode('node')->getAttribute('name')) {
             $attribute = $node->getNode('attribute');
-            if ($attribute instanceof Twig_Node_Expression_Constant && in_array($attribute->getAttribute('value'), ['length', 'revindex0', 'revindex', 'last'])) {
+            if ($attribute instanceof Twig_Node_Expression_Constant && \in_array($attribute->getAttribute('value'), ['length', 'revindex0', 'revindex', 'last'])) {
                 throw new Twig_Error_Syntax(sprintf('The "loop.%s" variable is not defined when looping with a condition.', $attribute->getAttribute('value')), $node->getTemplateLine(), $stream->getSourceContext());
             }
         }
diff --git a/lib/Twig/TokenParser/Set.php b/lib/Twig/TokenParser/Set.php
index 6c5bb5274..a7b79d52f 100644
--- a/lib/Twig/TokenParser/Set.php
+++ b/lib/Twig/TokenParser/Set.php
@@ -33,13 +33,13 @@ final class Twig_TokenParser_Set extends Twig_TokenParser
 
             $stream->expect(/* Twig_Token::BLOCK_END_TYPE */ 3);
 
-            if (count($names) !== count($values)) {
+            if (\count($names) !== \count($values)) {
                 throw new Twig_Error_Syntax('When using set, you must have the same number of variables and assignments.', $stream->getCurrent()->getLine(), $stream->getSourceContext());
             }
         } else {
             $capture = true;
 
-            if (count($names) > 1) {
+            if (\count($names) > 1) {
                 throw new Twig_Error_Syntax('When using set with a block, you cannot have a multi-target.', $stream->getCurrent()->getLine(), $stream->getSourceContext());
             }
 
diff --git a/lib/Twig/TokenStream.php b/lib/Twig/TokenStream.php
index d3ea2663d..cce9a9747 100644
--- a/lib/Twig/TokenStream.php
+++ b/lib/Twig/TokenStream.php
@@ -34,7 +34,7 @@ final class Twig_TokenStream
 
     public function injectTokens(array $tokens)
     {
-        $this->tokens = array_merge(array_slice($this->tokens, 0, $this->current), $tokens, array_slice($this->tokens, $this->current));
+        $this->tokens = array_merge(\array_slice($this->tokens, 0, $this->current), $tokens, \array_slice($this->tokens, $this->current));
     }
 
     /**
diff --git a/test/Twig/Tests/Cache/FilesystemTest.php b/test/Twig/Tests/Cache/FilesystemTest.php
index 818e3ece0..806143eeb 100644
--- a/test/Twig/Tests/Cache/FilesystemTest.php
+++ b/test/Twig/Tests/Cache/FilesystemTest.php
@@ -9,7 +9,7 @@
  * file that was distributed with this source code.
  */
 
-require_once dirname(__DIR__).'/FilesystemHelper.php';
+require_once \dirname(__DIR__).'/FilesystemHelper.php';
 
 class Twig_Tests_Cache_FilesystemTest extends \PHPUnit\Framework\TestCase
 {
@@ -36,7 +36,7 @@ class Twig_Tests_Cache_FilesystemTest extends \PHPUnit\Framework\TestCase
     {
         $key = $this->directory.'/cache/cachefile.php';
 
-        $dir = dirname($key);
+        $dir = \dirname($key);
         @mkdir($dir, 0777, true);
         $this->assertTrue(is_dir($dir));
         $this->assertFalse(class_exists($this->classname, false));
@@ -81,7 +81,7 @@ class Twig_Tests_Cache_FilesystemTest extends \PHPUnit\Framework\TestCase
      */
     public function testWriteFailMkdir()
     {
-        if (defined('PHP_WINDOWS_VERSION_BUILD')) {
+        if (\defined('PHP_WINDOWS_VERSION_BUILD')) {
             $this->markTestSkipped('Read-only directories not possible on Windows.');
         }
 
@@ -103,7 +103,7 @@ class Twig_Tests_Cache_FilesystemTest extends \PHPUnit\Framework\TestCase
      */
     public function testWriteFailDirWritable()
     {
-        if (defined('PHP_WINDOWS_VERSION_BUILD')) {
+        if (\defined('PHP_WINDOWS_VERSION_BUILD')) {
             $this->markTestSkipped('Read-only directories not possible on Windows.');
         }
 
@@ -143,7 +143,7 @@ class Twig_Tests_Cache_FilesystemTest extends \PHPUnit\Framework\TestCase
     {
         $key = $this->directory.'/cache/cachefile.php';
 
-        $dir = dirname($key);
+        $dir = \dirname($key);
         @mkdir($dir, 0777, true);
         $this->assertTrue(is_dir($dir));
 
@@ -167,7 +167,7 @@ class Twig_Tests_Cache_FilesystemTest extends \PHPUnit\Framework\TestCase
     public function testGenerateKey($expected, $input)
     {
         $cache = new Twig_Cache_Filesystem($input);
-        $this->assertRegExp($expected, $cache->generateKey('_test_', get_class($this)));
+        $this->assertRegExp($expected, $cache->generateKey('_test_', \get_class($this)));
     }
 
     public function provideDirectories()
diff --git a/test/Twig/Tests/EnvironmentTest.php b/test/Twig/Tests/EnvironmentTest.php
index 8c66b0e76..2302dd2a3 100644
--- a/test/Twig/Tests/EnvironmentTest.php
+++ b/test/Twig/Tests/EnvironmentTest.php
@@ -285,7 +285,7 @@ class Twig_Tests_EnvironmentTest extends \PHPUnit\Framework\TestCase
         $twig = new Twig_Environment($loader);
         $twig->addExtension($extension);
 
-        $this->assertInstanceOf('Twig_ExtensionInterface', $twig->getExtension(get_class($extension)));
+        $this->assertInstanceOf('Twig_ExtensionInterface', $twig->getExtension(\get_class($extension)));
         $this->assertTrue($twig->isTemplateFresh('page', time()));
     }
 
diff --git a/test/Twig/Tests/Node/ForTest.php b/test/Twig/Tests/Node/ForTest.php
index 20955c9ec..dadcf090f 100644
--- a/test/Twig/Tests/Node/ForTest.php
+++ b/test/Twig/Tests/Node/ForTest.php
@@ -26,7 +26,7 @@ class Twig_Tests_Node_ForTest extends Twig_Test_NodeTestCase
         $this->assertEquals($valueTarget, $node->getNode('value_target'));
         $this->assertEquals($seq, $node->getNode('seq'));
         $this->assertTrue($node->getAttribute('ifexpr'));
-        $this->assertEquals('Twig_Node_If', get_class($node->getNode('body')));
+        $this->assertEquals('Twig_Node_If', \get_class($node->getNode('body')));
         $this->assertEquals($body, $node->getNode('body')->getNode('tests')->getNode(1)->getNode(0));
         $this->assertFalse($node->hasNode('else'));
 
diff --git a/test/Twig/Tests/escapingTest.php b/test/Twig/Tests/escapingTest.php
index 66e3b7d11..7bbd92cfe 100644
--- a/test/Twig/Tests/escapingTest.php
+++ b/test/Twig/Tests/escapingTest.php
@@ -238,22 +238,22 @@ class Twig_Test_EscapingTest extends \PHPUnit\Framework\TestCase
     protected function codepointToUtf8($codepoint)
     {
         if ($codepoint < 0x80) {
-            return chr($codepoint);
+            return \chr($codepoint);
         }
         if ($codepoint < 0x800) {
-            return chr($codepoint >> 6 & 0x3f | 0xc0)
-                .chr($codepoint & 0x3f | 0x80);
+            return \chr($codepoint >> 6 & 0x3f | 0xc0)
+                .\chr($codepoint & 0x3f | 0x80);
         }
         if ($codepoint < 0x10000) {
-            return chr($codepoint >> 12 & 0x0f | 0xe0)
-                .chr($codepoint >> 6 & 0x3f | 0x80)
-                .chr($codepoint & 0x3f | 0x80);
+            return \chr($codepoint >> 12 & 0x0f | 0xe0)
+                .\chr($codepoint >> 6 & 0x3f | 0x80)
+                .\chr($codepoint & 0x3f | 0x80);
         }
         if ($codepoint < 0x110000) {
-            return chr($codepoint >> 18 & 0x07 | 0xf0)
-                .chr($codepoint >> 12 & 0x3f | 0x80)
-                .chr($codepoint >> 6 & 0x3f | 0x80)
-                .chr($codepoint & 0x3f | 0x80);
+            return \chr($codepoint >> 18 & 0x07 | 0xf0)
+                .\chr($codepoint >> 12 & 0x3f | 0x80)
+                .\chr($codepoint >> 6 & 0x3f | 0x80)
+                .\chr($codepoint & 0x3f | 0x80);
         }
         throw new \Exception('Codepoint requested outside of Unicode range.');
     }
@@ -269,7 +269,7 @@ class Twig_Test_EscapingTest extends \PHPUnit\Framework\TestCase
                 $this->assertEquals($literal, twig_escape_filter($this->env, $literal, 'js'));
             } else {
                 $literal = $this->codepointToUtf8($chr);
-                if (in_array($literal, $immune)) {
+                if (\in_array($literal, $immune)) {
                     $this->assertEquals($literal, twig_escape_filter($this->env, $literal, 'js'));
                 } else {
                     $this->assertNotEquals(
@@ -292,7 +292,7 @@ class Twig_Test_EscapingTest extends \PHPUnit\Framework\TestCase
                 $this->assertEquals($literal, twig_escape_filter($this->env, $literal, 'html_attr'));
             } else {
                 $literal = $this->codepointToUtf8($chr);
-                if (in_array($literal, $immune)) {
+                if (\in_array($literal, $immune)) {
                     $this->assertEquals($literal, twig_escape_filter($this->env, $literal, 'html_attr'));
                 } else {
                     $this->assertNotEquals(