diff --git a/.github/workflows/run-integration-tests.yml b/.github/workflows/run-integration-tests.yml
index cf342e4..99d77ca 100644
--- a/.github/workflows/run-integration-tests.yml
+++ b/.github/workflows/run-integration-tests.yml
@@ -18,7 +18,7 @@ jobs:
             COMPOSER_NO_INTERACTION: 1
         strategy:
             matrix:
-                php: [8.0, 7.4, 7.3]
+                php: [8.1, 8.0, 7.4, 7.3]
                 lumen: [8.*]
         name: P${{ matrix.php }} - Lumen${{ matrix.lumen }}
         steps:
@@ -75,7 +75,7 @@ jobs:
             COMPOSER_NO_INTERACTION: 1
         strategy:
             matrix:
-                php: [8.0, 7.4, 7.3]
+                php: [8.1, 8.0, 7.4, 7.3]
                 laravel: [8.*]
         name: P${{ matrix.php }} - Laravel${{ matrix.laravel }}
         steps:
diff --git a/.github/workflows/run-tests.yml b/.github/workflows/run-tests.yml
index cc32341..0355288 100644
--- a/.github/workflows/run-tests.yml
+++ b/.github/workflows/run-tests.yml
@@ -20,7 +20,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-20.04, windows-2019]
-        php: [8.0, 7.4, 7.3]
+        php: [8.1, 8.0, 7.4, 7.3]
         laravel: [8.*]
         dependency-version: [prefer-lowest, prefer-stable]
         exclude:
diff --git a/src/Console/ModelsCommand.php b/src/Console/ModelsCommand.php
index 2419061..fd2997b 100644
--- a/src/Console/ModelsCommand.php
+++ b/src/Console/ModelsCommand.php
@@ -1335,7 +1335,7 @@ class ModelsCommand extends Command
             $docComment ?? '',
             $matches
         );
-        $type = $matches[1] ?? null;
+        $type = $matches[1] ?? '';
 
         if (strpos($type, '|') !== false) {
             $types = explode('|', $type);
diff --git a/tests/Console/EloquentCommandTest.php b/tests/Console/EloquentCommandTest.php
index 322cbcd..3776f7f 100644
--- a/tests/Console/EloquentCommandTest.php
+++ b/tests/Console/EloquentCommandTest.php
@@ -45,14 +45,14 @@ class EloquentCommandTest extends TestCase
         $this->assertMatchesTxtSnapshot($actualContent);
 
         $display = $tester->getDisplay();
-        $this->assertRegExp(
+        $this->assertMatchesRegularExpression(
             ';Unexpected no document on Illuminate\\\Database\\\Eloquent\\\Model;',
             $display
         );
         $modelClassFilePath = preg_quote(
             str_replace('/', DIRECTORY_SEPARATOR, '/vendor/laravel/framework/src/Illuminate/Database/Eloquent/Model.php')
         );
-        $this->assertRegExp(
+        $this->assertMatchesRegularExpression(
             ';Wrote expected docblock to .*' . $modelClassFilePath . ';',
             $display
         );