diff --git a/CHANGELOG-6.x.md b/CHANGELOG-6.x.md
index fdc8dab6c..362094d29 100644
--- a/CHANGELOG-6.x.md
+++ b/CHANGELOG-6.x.md
@@ -2,6 +2,14 @@
 
 This changelog references the relevant changes (bug and security fixes) done to `orchestra/testbench-core`.
 
+## 6.49.1
+
+Released: 2024-03-15
+
+### Fixes
+
+* Fixes `class_implements(): Class AllowDynamicProperties does not exist and could not be loaded` error on PHP 8.1 and lower.
+
 ## 6.49.0
 
 Released: 2024-03-13
diff --git a/src/PHPUnit/AttributeParser.php b/src/PHPUnit/AttributeParser.php
index 26b6ca000..a9fecd419 100644
--- a/src/PHPUnit/AttributeParser.php
+++ b/src/PHPUnit/AttributeParser.php
@@ -79,6 +79,10 @@ public static function forMethod(string $className, string $methodName): array
      */
     public static function validAttribute($class): bool
     {
+        if (\is_string($class) && ! class_exists($class)) {
+            return false;
+        }
+
         $implements = class_implements($class);
 
         return isset($implements[TestingFeature::class])