diff --git a/composer.json b/composer.json
index c85c9d3..0f12fc0 100755
--- a/composer.json
+++ b/composer.json
@@ -18,14 +18,14 @@
     "require": {
         "php": "^7.1",
         "clue/stdio-react": "^2.2",
-        "illuminate/support": "5.6.*|5.7.*|5.8.*",
+        "illuminate/support": "5.6.*|5.7.*|5.8.*|^6.0",
         "laravel/tinker": "^1.0",
         "psy/psysh": "^0.9.9",
         "react/socket": "^1.2"
     },
     "require-dev": {
-        "orchestra/testbench": "3.7.*",
-        "phpunit/phpunit": "^7.0"
+        "orchestra/testbench": "3.7.*|^4.0",
+        "phpunit/phpunit": "^7.0|^8.0"
     },
     "autoload": {
         "files": [
diff --git a/src/helpers.php b/src/helpers.php
index 176d12e..b42a6e6 100644
--- a/src/helpers.php
+++ b/src/helpers.php
@@ -16,14 +16,14 @@ function tinker(...$args)
                 return file($filePath)[$lineNumber - 1];
                 // "    tinker($post, new User);"
             })->map(function ($carry) {
-                return str_before(str_after($carry, 'tinker('), ');');
+                return Str::before(Str::after($carry, 'tinker('), ');');
                 // "$post, new User"
             })->flatMap(function ($carry) {
                 return array_map('trim', explode(',', $carry));
                 // ["post", "new User"]
             })->map(function ($carry, $index) {
                 return strpos($carry, '$') === 0
-                    ? str_after($carry, '$')
+                    ? Str::after($carry, '$')
                     : 'temp'.$index;
                 // ["post", "temp1"]
             })