diff --git a/src/Illuminate/Foundation/Auth/Access/AuthorizesRequests.php b/src/Illuminate/Foundation/Auth/Access/AuthorizesRequests.php
index 13d3d9cd1ae4..7a13d37cfa67 100644
--- a/src/Illuminate/Foundation/Auth/Access/AuthorizesRequests.php
+++ b/src/Illuminate/Foundation/Auth/Access/AuthorizesRequests.php
@@ -2,6 +2,7 @@
 
 namespace Illuminate\Foundation\Auth\Access;
 
+use Illuminate\Support\Str;
 use Illuminate\Contracts\Auth\Access\Gate;
 
 trait AuthorizesRequests
@@ -81,7 +82,7 @@ protected function normalizeGuessedAbilityName($ability)
      */
     public function authorizeResource($model, $parameter = null, array $options = [], $request = null)
     {
-        $parameter = $parameter ?: snake_case(lcfirst(class_basename($model)));
+        $parameter = $parameter ?: Str::snake(lcfirst(class_basename($model)));
 
         $middleware = [];
 
diff --git a/src/Illuminate/Foundation/Console/TestMakeCommand.php b/src/Illuminate/Foundation/Console/TestMakeCommand.php
index 3c63323043fc..15b8cdf85368 100644
--- a/src/Illuminate/Foundation/Console/TestMakeCommand.php
+++ b/src/Illuminate/Foundation/Console/TestMakeCommand.php
@@ -2,6 +2,7 @@
 
 namespace Illuminate\Foundation\Console;
 
+use Illuminate\Support\Str;
 use Illuminate\Console\GeneratorCommand;
 
 class TestMakeCommand extends GeneratorCommand
@@ -49,7 +50,7 @@ protected function getStub()
      */
     protected function getPath($name)
     {
-        $name = str_replace_first($this->rootNamespace(), '', $name);
+        $name = Str::replaceFirst($this->rootNamespace(), '', $name);
 
         return $this->laravel->basePath().'/tests'.str_replace('\\', '/', $name).'.php';
     }
diff --git a/src/Illuminate/Foundation/helpers.php b/src/Illuminate/Foundation/helpers.php
index 496bcdff9864..9589a1f63de6 100644
--- a/src/Illuminate/Foundation/helpers.php
+++ b/src/Illuminate/Foundation/helpers.php
@@ -1,5 +1,6 @@
 <?php
 
+use Illuminate\Support\Str;
 use Illuminate\Support\Carbon;
 use Illuminate\Support\HtmlString;
 use Illuminate\Container\Container;
@@ -546,11 +547,11 @@ function mix($path, $manifestDirectory = '')
     {
         static $manifests = [];
 
-        if (! starts_with($path, '/')) {
+        if (! Str::startsWith($path, '/')) {
             $path = "/{$path}";
         }
 
-        if ($manifestDirectory && ! starts_with($manifestDirectory, '/')) {
+        if ($manifestDirectory && ! Str::startsWith($manifestDirectory, '/')) {
             $manifestDirectory = "/{$manifestDirectory}";
         }
 
diff --git a/src/Illuminate/Http/Resources/Json/Resource.php b/src/Illuminate/Http/Resources/Json/Resource.php
index 236db6d2359e..0d611f935617 100644
--- a/src/Illuminate/Http/Resources/Json/Resource.php
+++ b/src/Illuminate/Http/Resources/Json/Resource.php
@@ -4,6 +4,7 @@
 
 use ArrayAccess;
 use JsonSerializable;
+use Illuminate\Support\Arr;
 use Illuminate\Support\Collection;
 use Illuminate\Container\Container;
 use Illuminate\Http\Resources\MergeValue;
@@ -256,7 +257,7 @@ protected function mergeWhen($condition, $value)
     protected function attributes($attributes)
     {
         return new MergeValue(
-            array_only($this->resource->toArray(), $attributes)
+            Arr::only($this->resource->toArray(), $attributes)
         );
     }