diff --git a/src/Rector/v12/v0/tca/MigrateNullFlagRector.php b/src/Rector/v12/v0/tca/MigrateNullFlagRector.php
index 5da706238..1da5ad4b0 100644
--- a/src/Rector/v12/v0/tca/MigrateNullFlagRector.php
+++ b/src/Rector/v12/v0/tca/MigrateNullFlagRector.php
@@ -68,7 +68,7 @@ protected function refactorColumn(Expr $columnName, Expr $columnTca): void
 
         /** @var String_ $evalStringNode */
         $evalStringNode = $evalArrayItem->value;
-        $value = $evalStringNode->value;
+        $value = (string) $evalStringNode->value;
 
         if (! StringUtility::inList($value, 'null')) {
             return;
diff --git a/tests/Rector/v12/v0/tca/MigrateNullFlagRector/Fixture/fixture.php.inc b/tests/Rector/v12/v0/tca/MigrateNullFlagRector/Fixture/fixture.php.inc
index 8be1dbba9..f29b97149 100644
--- a/tests/Rector/v12/v0/tca/MigrateNullFlagRector/Fixture/fixture.php.inc
+++ b/tests/Rector/v12/v0/tca/MigrateNullFlagRector/Fixture/fixture.php.inc
@@ -21,6 +21,11 @@ return [
                 'nullable' => true,
             ],
         ],
+        'employment_type' => [
+            'config' => [
+                'eval' => ''
+            ],
+        ],
     ],
 ];
 
@@ -46,6 +51,11 @@ return [
         'already_nullable_column' => [
             'config' => ['nullable' => true],
         ],
+        'employment_type' => [
+            'config' => [
+                'eval' => ''
+            ],
+        ],
     ],
 ];