diff --git a/typo3/sysext/core/Tests/Functional/TypoScript/PageTsConfigFactoryTest.php b/typo3/sysext/core/Tests/Functional/TypoScript/PageTsConfigFactoryTest.php
index d0e34a6da0284b3e105b3b4cc831299e31de7c95..9b2569b1bcaa220ed97f1bb4fdcd97d92ab582c6 100644
--- a/typo3/sysext/core/Tests/Functional/TypoScript/PageTsConfigFactoryTest.php
+++ b/typo3/sysext/core/Tests/Functional/TypoScript/PageTsConfigFactoryTest.php
@@ -44,6 +44,18 @@ final class PageTsConfigFactoryTest extends FunctionalTestCase
         self::assertSame('loadedFromGlobals', $pageTsConfig->getPageTsConfigArray()['loadedFromGlobals']);
     }
 
+    /**
+     * @test
+     */
+    public function pageTsConfigLoadsSingleFileWithOldImportSyntaxFromGlobals(): void
+    {
+        $GLOBALS['TYPO3_CONF_VARS']['BE']['defaultPageTSconfig'] = '<INCLUDE_TYPOSCRIPT: source="FILE:EXT:test_typoscript_pagetsconfigfactory/Configuration/TsConfig/tsconfig-includes.tsconfig">';
+        /** @var PageTsConfigFactory $subject */
+        $subject = $this->get(PageTsConfigFactory::class);
+        $pageTsConfig = $subject->create([], new NullSite());
+        self::assertSame('loadedFromTsconfigIncludesWithTsconfigSuffix', $pageTsConfig->getPageTsConfigArray()['loadedFromTsconfigIncludesWithTsconfigSuffix']);
+    }
+
     /**
      * @test
      */
@@ -102,6 +114,23 @@ final class PageTsConfigFactoryTest extends FunctionalTestCase
         self::assertSame('loadedFromTsconfigIncludesWithTyposcriptSuffix', $pageTsConfig->getPageTsConfigArray()['loadedFromTsconfigIncludesWithTyposcriptSuffix']);
     }
 
+    /**
+     * @test
+     */
+    public function pageTsConfigLoadsSingleFileWithOldImportSyntax(): void
+    {
+        $rootLine = [
+            [
+                'uid' => 1,
+                'TSconfig' => '<INCLUDE_TYPOSCRIPT: source="FILE:EXT:test_typoscript_pagetsconfigfactory/Configuration/TsConfig/tsconfig-includes.tsconfig">',
+            ],
+        ];
+        /** @var PageTsConfigFactory $subject */
+        $subject = $this->get(PageTsConfigFactory::class);
+        $pageTsConfig = $subject->create($rootLine, new NullSite());
+        self::assertSame('loadedFromTsconfigIncludesWithTsconfigSuffix', $pageTsConfig->getPageTsConfigArray()['loadedFromTsconfigIncludesWithTsconfigSuffix']);
+    }
+
     /**
      * @test
      */
diff --git a/typo3/sysext/core/Tests/Functional/TypoScript/UserTsConfigFactoryTest.php b/typo3/sysext/core/Tests/Functional/TypoScript/UserTsConfigFactoryTest.php
index d029cd6df7c65f808fe89f9731d1b45ba5153358..0612b3d32f70964df0d3ed3131a71de1114aa1b7 100644
--- a/typo3/sysext/core/Tests/Functional/TypoScript/UserTsConfigFactoryTest.php
+++ b/typo3/sysext/core/Tests/Functional/TypoScript/UserTsConfigFactoryTest.php
@@ -42,6 +42,20 @@ final class UserTsConfigFactoryTest extends FunctionalTestCase
         self::assertSame('loadedFromGlobals', $userTsConfig->getUserTsConfigArray()['loadedFromGlobals']);
     }
 
+    /**
+     * @test
+     */
+    public function userTsConfigLoadsSingleFileWithOldImportSyntaxFromGlobals(): void
+    {
+        $GLOBALS['TYPO3_CONF_VARS']['BE']['defaultUserTSconfig'] = '<INCLUDE_TYPOSCRIPT: source="FILE:EXT:test_typoscript_usertsconfigfactory/Configuration/TsConfig/tsconfig-includes.tsconfig">';
+        $this->importCSVDataSet(__DIR__ . '/Fixtures/userTsConfigTestFixture.csv');
+        $backendUser = $this->setUpBackendUser(1);
+        /** @var UserTsConfigFactory $subject */
+        $subject = $this->get(UserTsConfigFactory::class);
+        $userTsConfig = $subject->create($backendUser);
+        self::assertSame('loadedFromTsconfigIncludesWithTsconfigSuffix', $userTsConfig->getUserTsConfigArray()['loadedFromTsconfigIncludesWithTsconfigSuffix']);
+    }
+
     /**
      * @test
      */